Green’s Dictionary of Slang

gentleman n.

[on pattern of citizen n. (1); alderman n. (5); lord mayor n.1 : smaller and larger versions of the tool]

(US Und.) a crowbar.

[UK] ‘Flash Lang.’ in Confessions of Thomas Mount 19: A crow bar, a gentleman.
[US]H. Tufts Autobiog. (1930) 292: Gentleman . . . a crow bar.
[UK]Farmer & Henley Sl. and Its Analogues.

SE in slang uses

In compounds

gentleman-usher (n.) [? pun on SE gentleman usher of the Black Rod; note Williams: ‘gentleman usher [...] a male attendant on a lady, sometimes providing a sexual or pimping service’]

1. the penis; cit. 1719 is a double entendre.

[UK] in D’Urfey Pills to Purge Melancholy III 6: Here Damsels are handled like Nymphs in the Bath, / By Gentlemen-Ushers, with Legs like a Lath.

2. a woman’s male companion.

Chapman [play title] Gentleman Usher.
[UK]Wandring Whore V 6: Go to bed with thy Gentleman-usher, and if he [husband] be angry, call him rogue, raskal, and jealous Cuckold.
[UK]T. Brown Amusements Serious and Comical in Works (1744) III 97: That cringing slave who is under the plague of being a gentleman-usher to a lame countess.

In phrases

gentleman in blue (and white) (n.) (also gent in blue) [the uniform]

a policeman.

[[UK]Exter & Plymouth Gaz. 29 Nov. 4/1: She was received by a military-looking gentleman in blue [...] the waterman pronounced him to be Sergeant Tims of the Metropolitan Police Force].
[Aus]Bell’s Life in Sydney 4 July 3/1: Certain blank looks were observable amongst the ‘gemmen’ in blue.
[UK]Paul Pry Jan. 1/2: [I]f the police were to force an entrance, the lights in the passage would be put out, and [...] a few ‘known bullies’ could keep back the ‘gentlemen in blue’ until every body else had escaped.
[Aus]Bell’s Life in Sydney 6 Nov. 3/1: Augustus Kean [...] performed a variety of monkeyish and bearish tricks [...] which called for the interposition of the gentlemen in blue.
[UK]Hotten Sl. Dict. 78: ‘The gentleman in blue and white’ – i.e., a policeman.
[UK]Western Gaz. 20 Feb. 3/3: he wants to know why a gentleman in blue was present.
[UK]Western Gaz. 11 Sept. 8/3: Shortly afterwards ‘a gentleman in blue’ arrived, and took the unhappy being into custody .
[Aus]Bulletin (Sydney) 8 May 6/2: He’s going to see whether his own word and that of fourteen hard-working witnesses won’t be preferred in a court of justice to the emphatic oath of the gentleman in blue.
[UK]Worcs. Chron. 6 Jan. 5/4: The news soon reached the village inn. [...] the local ‘gentleman in blue’ [...] quickly reached the spot.
[UK]Bird o’ Freedom 8 Jan. 2/4: He looked as if a good supper of stewed tripe and onions (to fill up the gaps of his ‘inner man’ with) would have been much more to his liking than singing ‘Rory O’More,’ for the chance of a stray penny, or a hint from a gentleman in blue, to ‘move on’.
[UK]Illus. Police News 4 Feb. 5/2: And a certain gent was sent for — you know the one I mean — / The gent in blue who promenades at night!
[UK]Western Times 26 July 5/2: [cartoon caption] The Chief Constable took the precaution to send ‘a gentleman in blue’ to prevent any violent collision.
[UK]Dundee Courier 30 May 7/2: The ‘gentleman in blue‘, who was quickly on the scene, was hoodwinked.
[UK]Derby Dly Teleg. 11 Oct. 6/3: Police and Public [...] The public is prepared to make a friend of the gentleman in blue and to help him.
gentleman in brown (n.)

a bedbug.

[UK]G.A. Sala in Daily Tel. 14 Aug. 5/3: Bed bugs, the convertible term for which is ‘chintzes,’ are the disagreeable insects known in modern polite English as ‘Norfolk Howards,’ or gentlemen in brown [F&H].
[UK]Farmer & Henley Sl. and Its Analogues.
gentleman in red (n.)

a soldier.

[UK]Lee in Burke’s Corr. (1844) I 513: We gentlemen in red never chose to remember that in all our defeats and disgraces [...] the provincials never led the flight .
gentleman of... (n.)

see separate entry.

gentleman’s (…) (n.)

see separate entry.

gentleman wants to take a chance (n.)

(US short-rder) a plate of hash.

[US]Ocala Eve. Star (FL) 20 June 1/5: ‘Hash,’ says a customer. ‘Gentleman wants to take a chance!’.
gentleman who pays the rent (n.)

(Irish) a pig.

[UK]Daily Tel. 17 Dec. in Ware (1909) 140/1: The Irish pig, the gentleman who pays the Irish rent, if not exactly a willing immigrant into this country, has always proved a quiet one after his arrival. He has generally been cured before leaving home.
[US]Chicago Trib. 20 Feb. 8/2: It is a surprise [...] to a visitor from Ireland in this country to hear cobwebs alluded to as ‘Irish draperies’ [...] ‘The gintleman that pays the rint’ doesn’t walk in and out of the house any more than he does here.