Green’s Dictionary of Slang

gum v.2

also gum up

1. (US) to mess up, to spoil.

[US]Yale Fun 27: The plot that was gummed [DA].
A. Baer Rabid Rudolph 4 Dec. [synd. col.] Nap got his name in the papers without every booting a field goal or gumming a forward pass.
[US]N-Y Tribune 22 Jan. 9/3: They rushed me out, so as I wouldn’t ‘gum the show’.
[US]H.C. Witwer Fighting Blood 208: When I stepped in and gummed up Rags Dempster’s plans.
[US](con. 1917–18) C. MacArthur War Bugs 47: The attack he nearly gummed up came off that morning.
[US]E. Anderson Hungry Men 62: Those old smoke belches from the Bowery are gumming it up.
[US]R. Chandler Lady in the Lake (1952) 51: Don’t use it [i.e. alcohol] myself. Never could understand folks letting themselves get gummed up with it.
[US]F. Brown Dead Ringer 141: Maybe you think by tossing away the eights to draw to your bullets, you gummed my draw.
[Aus]J. Walker No Sunlight Singing (1966) 23: That’s why that blue I had nearly gummed it up.
[US]Ragen & Finston World’s Toughest Prison 802: gum—To spoil; to interfere with; to upset a plan or arrangement.

2. to talk nonsense.

[US]J.L. Kuethe ‘Johns Hopkins Jargon’ in AS VII:5 332: gum—v.—to talk nonsense.
[US]Mad mag. Jan.–Feb. 48: I don’t want to double-O what Brutus gummed.

3. (US Black) to confess a crime.

[US]Pittsburgh Courier (PA) 8 Feb. 7/1: The law [...] lowered the boom on him [...] in the domicile of many slammers until he gummed.

In compounds

gumbrain (n.) (also gumbook, gumhead)

(US) an idiot.

[US]H. Ellison ‘Johnny Slice’s Stoolie’ in Deadly Streets (1983) 80: Man, was he soft in the head! A real gumbrain.
[US](con. 1958) R. Farina Been Down So Long (1972) 41: They ain’t your problems, gumbook.
[US]W. Kotzwinkle Jack in the Box 203: I’m alone with these two gum-heads.

In phrases

gum the game (v.) (also gum the play, ...show)

to spoil.

[US]O. Johnson Varmint 142: Well, he’s rotten. He gums the whole show.
[UK]A.G. Empey Over the Top ‘Tommy’s Dict. of the Trenches’ 294: ‘Gumming the game.’ Spoiling anything, interfering.
[UK]Wodehouse Leave it to Psmith (1993) 494: Only this afternoon my jinx gummed the game for me and threw a spanner into the prettiest little scenario.
[US]D. Hammett ‘Fly Paper’ Story Omnibus (1966) 52: I wouldn’t gum Joe’s play with her.
[US]‘Blackie’ Audett Rap Sheet 188: I didn’t want to take no chances of gumming their play by getting nose trouble over something that wasn’t my business.
[UK]Wodehouse Jeeves in the Offing 88: [I shall be] ready to pop out and gum the game.
gum (up) the works (v.) (also gum things up, gum up the game, ...inner workings, ...job)

to make a mess, to cause an obstruction.

[US]C. Coe Me – Gangster 200: The get-away has gotta depend on our not gummin’ the works.
[US]E.S. Gardner ‘Bird in the Hand’ in Goulart (1967) 273: That’s where you’ve always gummed the works before.
[US](con. 1920s) Dos Passos Big Money in USA (1966) 1066: You’re not going to try to gum up the game when I’ve got the biggest break I ever had in my life.
[UK]J. Curtis You’re in the Racket, Too 53: What are the waste materials, exactly, that you want me to buy and what price should I offer? I will have to straighten all that out or I will gum up the works.
[US]W.R. Burnett High Sierra in Four Novels (1984) 313: He’s got no business in a big-time job like this and he may gum the works.
[UK]‘Henry Green’ Loving (1978) 120: Why you’d gum up the whole works.
[US]P. Rabe Benny Muscles In (2004) 218: It also looked as if he was going to gum the works.
[Aus]J. Morrison Black Cargo 157: It isn’t wharfies and railwaymen who gum up the works.
[US]F. Elli Riot (1967) 101: A rumble with Fletcher could gum-up the works.
[Aus]F.J. Hardy Outcasts of Foolgarah (1975) 228: [He] put the kibosh on their conspiracy to gum up the inner workings.
[US](con. 1949) G. Pelecanos Big Blowdown (1999) 232: You don’t want to be gumming things up or yourself at this stage in the game.
W.R. Mead Special Providence 190: [...] the opportunities it gives for recalcitrant senators to gum up the works of the executive machine.
[US](con. 1954) ‘Jack Tunney’ Tomato Can Comeback [ebook] Stick to your newspaper stories, and quit tryin’ to gum up the works.