Green’s Dictionary of Slang

mouth n.

1. a fool, a dupe; thus you are a mouth and you will die a lip, a general phr. of abuse/dismissal.

Wandring whores complaint 4: I met with a Country Hick, and [...] we made a meer Mouth of him.
[UK]C. Cotton Compleat Gamester 8: The whole Gang will be ever and anon watching an opportunity to make a Mouth of you.
[UK]J. Poulter Discoveries 34: Another shall look out for a mouth that has a horse to sell or change .
[UK]Grose Classical Dict. of the Vulgar Tongue.
[UK]H.T. Potter New Dict. Cant (1795) n.p.: mouth a foolish easy fellow.
[UK]New Cheats of London Exposed 20: When they hit off the cully [...] they come to a convenient place where the mouth, as they term him, must needs observe.
[UK]G. Andrewes Dict. Sl. and Cant.
[UK]Lex. Balatronicum.
[UK]‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc.
[UK]G. Kent Modern Flash Dict.
[UK]Flash Dict. in Sinks of London Laid Open.
[US]Matsell Vocabulum.

2. (also mouther) a noisy, talkative, boorish person; thus rank mouth, an especially impudent person.

[UK]B.E. Dict. Canting Crew n.p.: Mouth a noisy Fellow.
[UK]New Canting Dict. [as cit. c.1698].
[UK]Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
[UK]Grose Classical Dict. of the Vulgar Tongue.
[UK]Lex. Balatronicum.
[UK]Egan Grose’s Classical Dict. of the Vulgar Tongue.
[UK]W.T. Moncrieff Heart of London II i: A rank mouth like you – you’d snitch on anyone for a glass of rum.
[US]Matsell Vocabulum.
[UK]Ally Sloper’s Half Holiday 3 May 3/1: McMouther [...] was raving like a maniac, and kicking the clouds about in savage fury.
[US]Berrey & Van den Bark Amer. Thes. Sl.
[Ire]T. Murphy Whistle in the Dark Act II: Our intelligent brother wants it seven to three. Our intelligent brother is warning him to keep away from us trash. Well, mouth, what about the eighth Mulryan?
[Ire]C. Brown Down All the Days 134: ‘Want to be on that, you mouth?’ answered Charlie, getting red and indignant.
[NZ]V.G. O’Sullivan Boy, The Bridge, The River 81: He gave the Buffs up soon enough, ‘Lot of mouthers,’ he said.
[US]R. Campbell Alice in La-La Land (1999) 57: A running mouth who’d somehow escaped the wrath of the mob by telling as many tales on the cops as on the families.
[UK]G. Iles Turning Angel 119: ‘No one’s supposed to talk about what happens in the grand jury room, but that’s probably all those girls are talking about.’ [...] ‘Oh definitely. They’re major mouths.’.
[UK]K. Sampson Killing Pool 7: The main mouth, DC Manners, is sidling over now, and there’s nothing less than unadulerated malice emanating from his twitchy, blinking face.

3. cheek, impudence, verbosity.

implied in give (it) mouth
[UK]Farmer & Henley Sl. and Its Analogues.
[US]Z.N. Hurston Mules and Men (1995) 34: She got plenty hips, plenty mouf and no brains.
[UK]W. Eyster Far from the Customary Skies 196: You’re all mouth.
[UK]L. Dunne Goodbye to The Hill (1966) 130: She had too much mouth. All talk.
[US](con. 1960s) D. Goines Black Gangster (1991) 283: Your bitch has got too much mouth.
[UK]A. Payne ‘Get Daley!’ Minder [TV script] 28: What a lot of mouth for a man in a serious predicament.
[Aus]R.G. Barrett Real Thing 173: He was credited with being 90 per cent mouth and 10 per cent ability.
[UK]Guardian 14 Sept. 1: Here comes Imran [...] full of mouth, sauntering late into class with a bag of crisps, stopping to chat to friends.
[US] M. McBride Frank Sinatra in a Blender [ebook] Telly told him to go fuck his father. Sid didn’t like that; he was tired of Telly’s mouth.

4. the dry, foul-tasting mouth that follows a night’s excesses; thus have a mouth on one, to be desperate for alcohol.

[Ire]C.J. Kickham Knocknagow 150: ‘This is the second three half-pints I’m goin’ for for ’em,’ she added; ‘though they never as much as axed me had I a mouth on me.’.
[Aus]Dead Bird (Sydney) 3 Aug. 3/3: ‘I say, why don’t you ask a man if he has a mouth on him’.
[UK]H.G. Wells Kipps (1952) 88: He awoke with what Chitterlow had pronounced to be, quite indisputably, a Head and a Mouth.
[Aus]Bulletin (Sydney) 7 July 10/2: At a Sydney hotel [...] there was a daylight robbery of a large sum of money. [...] The detectives were called in, and they came in droves. No one officer seemed to have the case in hand; half the force just called from time to time, and was asked if it had a mouth on it.
[UK]‘William Juniper’ True Drunkard’s Delight.

5. (US) a lawyer.

[UK]Farmer & Henley Sl. and Its Analogues.
[US]‘Hy Lit’ Hy Lit’s Unbelievable Dict. of Hip Words 41: the man’s mouth – Lawyer.

SE in slang uses

In derivatives

In compounds

mouth almighty (n.)

a noisy, talkative, loud-mouthed person.

[UK]Sporting Mag. Sept. XVI 256/1: Our old Bartholomew Fair acquaintance, Swords, nicknamed Mouth Almighty [...] was cryer to a Thespian Booth. [...] His bellowing was so harmonious, and his tremendous vortex so wide [etc.].
[UK]Sam Sly 28 Apr. 3/1: We advise Mr. M—p—t, alias Mouth Almighty, alias the hand- some counter-jumper, not to be seen in the King’s-road with dissolute female characters.
[UK]Hotten Sl. Dict.
[UK]Sl. Dict.
[Ire]Joyce Ulysses 691: He had the impudence to make up to me one time well done to him mouth almighty.
[Ire](con. 1930s–50s) É. Mac Thomáis Janey Mack, Me Shirt is Black 106: Mouth almighty. There’s only one mouth bigger than yours, it’s Portsmouth.
[UK]J. Sullivan ‘Wanted’ Only Fools and Horses [TV script] Is it true that mouth almighty over there has got the contract?
[UK]G. Burn Happy Like Murderers 46: But they – that is to say he – had a way with the chat. Mouth almighty.
mouth artist (n.) [-artist sfx]

1. (US) a braggart, an empty boaster.

[US](con. 1900s) S. Lewis Elmer Gantry 111: He’d show ’em! Some of these fellows that thought he was just a mouth-artist!

2. (US) a talented fellator/fellatrix.

[US](con. 1940s) C. Bram Hold Tight (1990) 145: He wanted to feel contemptuous of Hank for being such a mouth artist.
mouth bet (n.) (also mouth-betting)

(US gambling) a verbal promise of a bet.

[US] in Detroit Free Press n.p.: ‘Then, governor. I see you ten dolIars and raise you the whole State of Vermont.’ The game ceased. Mouth-betting was not a success [B&L].
[UK]Barrère & Leland Dict. of Sl., Jargon and Cant.
mouth breather (n.)

see separate entry.

mouth diarrhoea (n.)

the act of informing.

[US]E. Bunker No Beast So Fierce 69: A passer was caught, and in the police station had an attack of mouth diarrhea.
mouth fuck

see separate entries.

mouth half-cocked (n.) (also mouth half-cock) [fig. use of half-cocked, of a pistol that has the cock drawn back]

a person who gapes stupidly at anything and everything.

[UK]B.E. Dict. Canting Crew n.p.: Mouth half Cocks, gaping and staring at every thing they see.
[UK]New Canting Dict. n.p.: Mouth half Cockt, gaping and staring at every Thing they see.
[UK]Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
[UK]Grose Classical Dict. of the Vulgar Tongue (2nd, 3rd edn).
[UK]Lex. Balatronicum.
[UK]Egan Grose’s Classical Dict. of the Vulgar Tongue.
mouth music (n.)

the practice of cunnilingus.

[UK]D. Powis Signs of Crime 193: Mouth music A taboo and gross expression meaning the practice of cunnilingus. Never used in mixed or family company.
[UK]J. Morton Lowspeak.
mouth-off (n.)

(orig. US) a braggart, a boaster, a chatterer.

[US]R. Stone Hall of Mirrors (1987) 202: You’re a drunk, you’re cowardly, you’re a mouthoff.
mouth organ (n.) [puns] (US)

1. a spokesman.

in Bill Nye’s Western Humor (1968) 13: Secretary Spates, the silver-tongue orator and gilt-edged mouth organ of Wyoming.

2. the tongue.

[US]Maines & Grant Wise-crack Dict. 11: Mouth organ – the tongue.
mouthpiece (n.)

see separate entry.

mouth-talk (n.)

(US black) impulsive or thoughtless talk.

[US]A. Bontemps God Sends Sun. 104: ‘Damn ’em all, all de womens! I b’lieve Florence is bad luck to me anyhow.’ But that was just mouth-talk. He had hardly spoken the words when he wondered if he were not actually losing his mind about her.
mouthwash (n.)

see separate entries.

mouthwork (n.)

(US) bragging, boastfulness, empty words.

[US]W.P. McGivern Big Heat 122: Hee knew Bannion was ready to kill him; this wasn’t just mouthwork.
mouth-worker (n.)

1. (gay, also mouth queen) a fellator.

[US]G. Legman ‘Lang. of Homosexuality’ Appendix VII in Henry Sex Variants.
[US]Guild Dict. Homosexual Terms 31: mouthworker (n.): A fellator.
[US]B. Rodgers Queens’ Vernacular 52: fellator [...] mouth queen [worker].

2. (drugs) one who takes drugs orally.

[US]E. & S. Deak Grand Dictionnaire d’Americanismes.
[US] cited in Spears Sl. and Jargon of Drugs and Drink (1986).
[US]ONDCP Street Terms 15: Mouth worker — One who takes drugs orally.

In phrases

all mouth and trousers (adj.) (also all mouth; all mouth and no trousers)

all talk and no action, a braggart, a fake.

L.P. Hartley in Adam XXVIII-XXIX 34: Most men are all mouth and trousers — well, I like the trousers best, if you see what I mean.
[UK]J. Speight ‘I Can Give it Up Anytime I Like’ Till Death Us Do Part [TV script] See, he can’t – he’s all mouth and trousers.
[Can]R. Caron Go-Boy! 100: It turned out that Gordon was all mouth and no longer wanted to exit [...] on a stretcher.
[UK]S. Berkoff West in Decadence and Other Plays (1985) 134: Where were you, deserted me ye men of little faith / all mouth and trousers when it comes down to the crunch.
[Aus]Smith & Noble Neddy (1998) 223: When I fronted him over it, he tried to bluff me. [...] I tested him out and found that he is all mouth and very little ability to back it up.
[UK]I. Welsh Filth 65: Aw mooth n nae troosers that prick.
[UK]N. Barlay Hooky Gear 162: Still all mouf innit.
[Aus]P. Carey Theft 149: He was all piss and wind [...] all mouth and trousers.
[UK]email to Guardian 7 Feb. [Internet] Just some snotty nosed little toss rats, whose closest relationship to a women is Mrs Palm and her 5 daughters [...] all mouth and no trousers.
dip one’s mouth in someone’s business (v.)

see under dip v.2

don’t let your (alligator) mouth overload your ass(hole) [alligator mouth under alligator n.]

(US) keep quiet, esp. in a difficult situation where words might complicate matters; the phr. is variable, ass often being prefaced by a type of bird, e.g. don’t let your alligator mouth overload your canary ass.

[US]E. Folb Urban Black Argot 137: Don’t Let Your mouth Overload Your Ass don’t talk too much.
[US]E. Folb Runnin’ Down Some Lines 44: Don’t let your mouth overload your ass [...] refers to provocative talk.
C.H. Haseloff Ride South! 150: Don’t let your alligator mouth overload your jaybird ass.
W. Karlin Rumors and Stories 55: Don’t let your alligator mouth overload your lizard ass and all that other kind of Vietnam talk.
[US]E. Little Another Day in Paradise 37: Don’t let your three-hundred-pound mouth overload your hundred-and-thirty-pound ass.
P. Abresch Bloody Bonsai 49: A familiar kid’s saying came back to him from his childhood days: Don’t let your alligator mouth overload your canary ass.
[US]G. Pelecanos Right As Rain 287: I knew his mouth was overloadin’ his asshole, man, but with the alcohol runnin’ through me and shit —.
Black Belt (LA) Feb. 97/2: Moral: Don’t let your alligator mouth overload your canary tail feathers.
J.W. Huffman Wayward Wind 255: Mr. Harte, I recommend you don’t let your alligator mouth overload your mockingbird ass in the future.
don’t let your mouth buy what your ass can’t pay for

(US) keep quiet, esp. when speaking might make matters worse.

[US]E. Folb Urban Black Argot 137: Don’t Let Your Mouth Buy What Your Ass can’t Pay For don’t talk so much.
[US]C. Major Juba to Jive.
don’t let your mouth write a cheque your ass can’t cash

(orig. US black) keep quiet, esp. when speaking might make matters worse.

[US]H. Crews Car 60: Someday, if you’re not careful, you’ll write a check with your mouth that your ass can’t cash.
B. Webster One by One 29: You shouldn’t let your mouth write a check that your muscle can’t cash.
[US]E. Folb Runnin’ Down Some Lines 44: Don’t let your mouth write a check your ass can’t cash refers to provocative talk [...] that can often lead to a fight.
C. Portis Norwood 184: Don’t let your mouth write a check that your ass can’t cash, son.
[US]T.R. Houser Central Sl. 58: write checks you can’t cash To make boasts you cannot back up. To make promises you cannot keep. To talk stuff. ‘Don’t come around here and be writin’ no checks you can’t cash; you jump bad, we’ll kick your ass!’.
R. Vaughan Cold War 42: Now, just hold it right there, Lieutenant, before you let your alligator mouth write a check your hummingbird ass can’t cash.
C. Brookmyre One Fine Day (1999) 62: His mooth was aye writin’ cheques his arse couldnae cash.
E. Davis Snitchcraft 80: Candace stepped closer to Dee [...] and very calmly said, “Don’t let your mouth write a check your ass can’t cash.
give (it) mouth (v.)

to be cheeky.

[UK] ‘’Arry on Himself’ in Punch 21 Dec. in P. Marks (2006) 6: Mayn’t a cove give it mouth ’cos his patter ain’t up to Pall Mall?
[UK] ‘New Year’s Day’ in Pearl Christmas Annual 70: Why don’t you give it mouth, Simpson, as you did when you abused me and Mrs. Jones?
[UK]W. Hall Long and the Short and the Tall Act I: bamforth: You going to inspect us, Corp? / johnstone: Don’t give me any of your mouth.
[US]Hall & Adelman Gentleman of Leisure 148: I used to give Silky mouth.
[UK]I. Welsh Filth 49: Chinko’s been giein it loadsay fuckin mooth awright.
have a mouth like an abo’s armpit (v.)

(Aus.) to experience the dry mouth, furred tongue and disgusting taste that can accompany a hangover .

[Aus]C. Bowles G’DAY 88: Shane is not feeling too clever when he wakes up. He has a mouth like an abo’s armpit.
have a mouth like an Arab’s jockstrap (v.) (also ...like an Arab’s arse/sandal/sandshoe, ...like a Greek wrestler’s jockstrap, ...like the inside of a Pommie’s jockstrap) [stereotyping]

to experience the dry mouth, furred tongue and disgusting taste that can accompany a hangover.

[Aus]R.G. Barrett You Wouldn’t Be Dead for Quids (1989) 148: His mouth tasted like an Iranian tank driver’s jock strap.
[Aus]G. Seal Lingo 87: Many Lingo terms refer to, involve, or name parts of the human body [...] We may [...] have a mouth like the bottom of a birdcage, or like a greek wrestler’s jockstrap.
Kerrang! 18 Sept. [Internet] Dave Grohl is hung over. Not just slightly groggy hung-over, but full-on mouth-like-an-Arab’s-sandshoe-I-want-to-die-now hung-over.
‘Hungover Gloss.’ at HairyTongue.com [Internet] Mouth like an Arab’s sandal [phrase.] [...] Mouth like an Arabs jock strap [phrase.] [...] Mouth like Badgers Arse [phrase.] [...] 511. Mouth like Gandhi’s flip-flop [phrase.] [...] 512. Mouth like Mother Theresa’s flip flop.
Supple.co.uk 23 Aug. [Internet] I wasn’t drunk on it, but later that night I woke up with a mouth like an Arab’s arse, so had to crawl downstairs and drink a few gallons of water.
[NZ]McGill Reed Dict. of N.Z. Sl. 137: mouth like the inside of a Pommie’s jockstrap Rank, fuzzed taste from too much booze the night before. ANZ.
have a mouth like a (Turkish) wrestler’s jockstrap (v.)

to be severely hungover, suffering the effects of a heavy night’s drinking; also as one’s mouth is like….

[UK]‘P.B. Yuill’ Hazell and the Three-card Trick (1977) 188: Cor, me north an’ south is like a wrestler’s jockstrap.
[UK]G. Melly Rum, Bum and Concertina (1978) 118: Next day we awoke with splitting headaches and mouths like turkish wrestlers’ jockstraps.
have a mouth like the bottom of a birdcage (v.) (also ...a parrot’s cage) [the filthiness of the cage]

to be suffering the physical results of a night’s drinking; also as one’s mouth feels like...

[US]A. Baer Two and Three 17 Jan. [synd. col.] No more will we wake up [with] our mouths tasting like the bottom of a parrot’s cage.
[UK] Manchon Le Slang.
[US]I. Shulman Cry Tough! 83: ‘Christ,’ [...] you look like the bottom of a bird cage. What the hell’s the matter with you?’ ‘I told you,’ Mitch said. ‘I got drunk Saturday night and I’ve been feeling lousy ever since.’.
[Aus]Cusack & James Come in Spinner (1960) 109: I’ve got a mouth like the bottom of a birdcage.
[Aus]‘Neville Shute’ On the Beach 56: I’ve got a mouth like the bottom of the parrot’s cage.
[NZ]G. Slatter Gun in My Hand 232: Bloody awful. Mouth like the bottom of a birdcage.
[Aus]G. Seal Lingo 87: Many Lingo terms refer to, involve, or name parts of the human body [...] We may [...] have a mouth like the bottom of a birdcage, or like a greek wrestler’s jockstrap.
have a mouth like the bottom of a cocky’s cage (v.) (also ...a cockie’s cage) [SE cockatoo]

(Aus.) to have a mouth that is unpleasantly furred, the result of excessive drinking.

[Aus]I. Hamilton Till Human Voices Wake Us 79: Don’t go no a hunger strike after a spell of bread and water. Your tongue’s like the bottom of a cocky’s cage.
[Aus]F.J. Hardy Legends from Benson’s Valley 26: I awoke with a mouth like the bottom of a cockie’s cage.
[Aus]D. Ireland Unknown Industrial Prisoner 8: His tongue was still cocky caged from the night before.
[Aus]R. Beckett Dinkum Aussie Dict. 15: One is said to have ‘a mouth like the bottom of a cocky’s cage’ when one is suffering from a terminal hangover.
[Aus]A. Skerman Beyond Indigo 283: The condition your mouth must be in, anything’d taste like the floor of Cocky’s cage.
[Aus]M. Moody Sweet Surrender 99: I literally had no saliva in my mouth and no matter how much water I drank I still felt as though my mouth was, to use that delightful Australian phrase, like the bottom of a cocky's cage.
have a mouth (on one) (v.)

1. to be foul-mouthed or abusive; to be aggressively cheeky.

[UK] ‘’Arry on Marriage’ in Punch 29 Sept. 156/1: Great Scott, wot a patter he ’ad, and a mouth on ’im, ah! like the doose!
[US]G.V. Higgins Digger’s Game (1981) 143: You really got a mouth on you like a fuckin’ sewer.
[US]R. Campbell In La-La Land We Trust (1999) 22: ‘You’ve got a mouth.’ ‘You men teach us how to talk dirty, then you flinch.’.
[UK]G. Burn Happy Like Murderers 84: Hello Mr. Plod. Cunt. Oh, already she had a mouth on her.
[US]G. Pelecanos Night Gardener 113: Had a mouth on her, too. They was arguing over shit the whole time.
[US](con. 1973) C. Stella Johnny Porno 23: You got a mouth on you, you know that?

2. (Aus./Irish) to be thirsty; usu. as interrog. do you have a mouth on you? would you like a drink?

[Aus]J. Furphy Such is Life 11: A man that sets down to his dinner without askin’ another man whether he’s got a mouth on him or not!
[Ire]‘Myles na gCopaleen’ Best of Myles (1968) 241: That chancer was never in his life known to have asked a pal if he had a mouth on him.
[UK]S. Murphy Stone Mad (1966) 226: Did I hear somewan saying had I a mouth on me?
hold one’s mouth (v.)

to be quiet; usu. as imper.

[US]Lantern (N.O.) 14 May 2: [She] is to receive new shoes for holding her mouth and say nothing of what she saw.
[UK]Boy’s Own Paper 27 Nov. 133: Hold your mouth, you one-eyed old tater-grubber.
[US]M. Sandoz Jules 280: Hold your mouth [DARE].
[UK]Dizzee Rascal [song title] Hold Ya Mouf.
make mouths (at) (v.)

to speak insolently (to).

[UK]Shakespeare Hamlet II:2: Those that would make mouths at him while my father lived give twenty, forty, fifty, a hundred ducats apiece for his picture in little .
[UK]Etherege Man of Mode I i: dorimant: The nasty refuse of your shop. orange-woman: You need not make mouths at it, I assure you ’tis all culled ware.
[UK]‘Phoebe Crackenthorpe’ Female Tatler (1992) (3) 7: The girl, perceiving, made mouths at her, and hoyden’d out of the room.
make a wry mouth (v.) [the rictus of suffocation, ult. SE make a wry mouth, to grimace with disapproval]

to be hanged.

[UK]R. Bernard (trans.) in Terence Eunuch IV iv: Howe the hangman makes a wrie mouth [OED].
[UK]R. Cotgrave Dict. of Fr. and Eng. Tongues.
[UK]T. Brown Amusements Serious and Comical in Works (1744) III 62: A wry mouth on the triple tree puts an end to all discourse about us.
mout-hab-nuttin-fe-do (n.) [lit. ‘mouth has nothing (better) to do’]

(W.I.) a chatterbox, a malicious gossip.

[WI]cited in Cassidy & LePage Dict. Jam. Eng. (1980).
mouth runs like parch benny (adj.) (also mouth runs like sick nigger takes salts) [Carib.E. parch = SE parched + benny, a form of sesame-based cooking oil, used in making sweets]

(W.I.) a phr. used of an incessant irritating chatterer.

[WI]Allsopp Dict. Carib. Eng. Usage.
mouth that cannot bite (n.) [literary euph. coined by Thomas D’Urfey (1653–1723)]

the vagina.

[UK] in D’Urfey Pills to Purge Melancholy IV 71: My pretty Maid, fain would I know / What thing it is will breed Delight, / That strives to stand, yet cannot go, / That feeds the Mouth that cannot bite.
put one’s mouth on/upon (v.)

(W.I.) to denigrate, to slander .

[US]H.G. Murray ‘Tom Kittle’s Wake’ in D’Costa & Lalla Voices in Exile (1989) 100: He have her the weight of his fist the moment she attempted to ‘put her mout’ upon him.
[UK]T. White Catch a Fire 147: The rude boys [...] ‘put mout’ on’ (cursed out each other) to win the attentions of some stupid girls.
run one’s mouth (off) (v.) (also run one’s gab, run one’s gums) [one’s mouth runs like an engine] (orig. US/W.I.)

1. to gossip, to tell tales.

[US]Louis Armstrong [instrumental title] You Run Your Mouth, I’ll Run My Business.
[US]Z.N. Hurston Seraph on the Suwanee (1995) 726: Jim was off somewhere. Could be down there in the grove running his mouth off with Alfredo.
[US]‘Ed Lacy’ Lead With Your Left (1958) 50: You can get into trouble by talking too damn much. Know who you’re talking to before you run your gums.
[US]‘Ed Lacy’ Room to Swing 113: Sorry, boy, I shouldn’t have run my mouth like that.
[US](con. WWII) J.O. Killens And Then We Heard The Thunder (1964) 95: You run your big fat ignorant mouth and me and Professor Solly gon run our business.
[US]A. Brooke Last Toke 53: ’Bout time you be listenin’ ’stead o’ keep runnin’ you mouth.
[US]R. Campbell In La-La Land We Trust (1999) 55: It could be he called her Bouche because her mouth was pretty, because she ran it all the time, or because it was her sexual speciality.
[US]S. Morgan Homeboy 378: It was Savage [...] who run his mouf how the plaguers oughta be taken out to the range n shot.
[US]Eminem ‘Marshall Mathers’ [lyrics] Now everybody wanna run they mouth / and try to take shots at me.

2. to give advice.

[US]Louis Jordan ‘You Run Your Mouth and I’ll Run My Business’ [lyrics] You always tellin’ me what to do, / Sayin’, ‘I wouldn’t do that if I was you!’ / You run your mouth and I’ll run my business, brother.
[US]H.S. Thompson letter 23 Aug. in Proud Highway (1997) 393: My impression is that one American working with his hands in Latin America is worth ten running their mouths.
[US]O. Hawkins Ghetto Sketches 17: The one that’s always runnin’ his damned mouth is walkin’ off.
[US]E. Bunker Mr Blue 148: ‘Don’t run your mouth,’ he said. ‘Just listen for a minute.’.

3. to talk without restraint.

[US]J.D. Corrothers Black Cat Club 128: Let de man talk, can’t you? You allus runnin’ yo’ gab!
[US]R.M. Lindner Stone Walls and Men 356: If you talked in your sleep it meant court and you were therefore charged with ‘running your mouth’ in the dormitory.
[US]E. Gilbert Vice Trap 40: Shirley ran her mouth too much. She talked a streak.
[US]M. Baker Nam (1982) 145: This guy is running his mouth. You can’t keep him from talking. You’d have to gag him to make him shut up.
[US]S. King Dolores Claiborne 65: She ran her mouth until she got all tuckered out.
[US]Simon & Zorzi ‘Unconfirmed Reports’ Wire ser. 5 ep. 2 [TV script] He got a big fuckin’ mouth. An’ you need to stop runnin’ your own mouth, young’un.

4. as run up one’s mouth, to brag, to boast, to fantasize.

[UK](con. 1979–80) A. Wheatle Brixton Rock (2004) 102: He reckons he’s having a party next week, but I feel so he’s running up his mout’.
[UK]Taskforce ‘Remus Returns’ [lyrics] You’re only starting out / So do not run your mouth.
[US]G. Hayward Corruption Officer [ebk] cap. 36: Now the inmate was openly challenging me [...] I sat back in my seat and just weatched him run his mouth.
set mouth on (v.)

(US black) to gossip, to malign.

[US]E. Folb Runnin’ Down Some Lines 198: There were terms related to gossip and those who gossiped: set mouth, snipe [...] (gossip, talk badly about someone).