Green’s Dictionary of Slang

GI adj.

[ult. US milit. abbrev. galvanized iron, reinterpreted in WW1 to government issue. For detailed over view see https://wordorigins.substack.com/p/gi-gi-joe]

SAmE in slang uses

In compounds

GI gin (n.)

(orig. US milit.) cough syrup with a high alcohol content popular with addicts when heroin supplies are short.

Listen 7-10 167: In the Army, ETH is called ‘GI gin’ and is taken by the bottle by unwary soldiers. When a friend of mine went to a drugstore, she asked the pharmacist to recommend something for her three-year-old boy's cough. He brought out a bottle of terpin.
US Army Court Martial Records 29 416/2: As for the cough syrup popularly referred to as ‘GI gin,’ the evidence showed it to be elixir terpin hydrate which contains codein.
[US]R. Moore Green Berets 133: I reached swiftly into the pocket of my loose jungle fatigues for the bottle of GI gin.
Winek Drug Abuse 136: Terpin hydrate and codeine elixir...contains 43% alcohol. That’s 86 proof! This is the stuff called ‘GI Gin.’ It...is popular among addicts during dry spells of heroin [HDAS].
[US]Hardy & Cull Drug Lang. and Lore.
Hearings for H.R. 1613—the Atomic Veterans Relief Act 45: We got 2 ounces of ‘GI gin’ and two aspirins and went back to work.
Future of Health Care in America 650: When he went for medical help he was given two aspirin and ‘GI gin’ and told to report for duty.
GI haircut (n.)

(US) a very short haircut, imported into civilian life by former soldiers.

letter in J. Hagedorn There’ll Come a Day: Letters from A G.I. 271: Get a GI haircut once – then you’ll have something to complain about.
[US]J.L. Riordan ‘Some “G.I. Alphabet Soup”’ in AS XXII:2 Apr. 113: G.I. haircut (or: bob)18 [18. Very short haircut given to new recruits].
in D. Carson Grit, Noise, And Revolution n.p.: My dad took me to the barber shop and made me get a GI haircut.
GI Jane (n.)

(US) a female member of the armed forces.

N.Y. Times Mag 17 Sept. 32: G.I. Jane. A member of the WAC [HDAS].
[US]Newsday 23 Jun. [CNN-TV] Do GI Janes deserve a place on the battlefield? [HDAS].
Nestle & Wilchins Genderqueer 123: My English teacher, a homophobic straight man who referred to me as ‘GI Jane’.
GI Joe (n.) (also Joe)

1. (US) a male American soldier; thus G.I. Jane, a female soldier.

[US] in Our Army Oct. 46: G.I. Joe wants to know if steel wool comes from hydraulic rams.
[Scot]Aberdeen Jrnl 5 Aug. 1/5: People are asking why the American Tommy Atkins is now generally known as ‘G.I. Joe’ rather than [...] ‘Doughboy’.
[US]J.W. Bishop ‘American Army Speech’ in AS XXI:4 Dec. 248: G.I. Joe is frowned upon (although a soldier unknown to the speaker may be, as in civilian life, referred to as ‘a Joe’ or ‘some Joe’) and is found only in advertising copy, the stories of the sloppier sort of correspondent and the orations of Clare Boothe Luce.
[US](con. 1944) J.H. Burns Gallery (1948) 13: Joe! Gimme caramelle! the baby called.
[Scot]Sun. Post (Lanarks) 24 Dec. 1/5: In West Germany ‘G.I. Joe’ was playing Father Christmas to over 100,000 needy German children.
[UK]J. Maclaren-Ross ‘Astrid’ in Bitten by the Tarantula (2005) 272: The tawdry suburban typists [...] determinedly pursuing G.I. Joe up and down London Town.
[US](con. 1951) McAleer & Dickson Unit Pride (1981) 177: Want to get laid, Joe?
[US]R. Price Ladies’ Man (1985) 73: I have [...] a GI Joe doll with removable clothes and weapons.
[US](con. c.1967) J. Ferrandino Firefight 33: ‘Sure, Joe, sure,’ the kid [Vietnamese] said.
[US]S. King Tommyknockers (1989) 343: He had spoken one phrase quite clearly: ‘All the G.I. Joes’.
[UK]Indep. 10 Jan. 3: A latter-day Madame Butterfly meets her GI Joe during the fall of Saigon.
Negus Who Read Feb. 🌐 Trump [...] harbors no qualms about sending GI Joe and Jane to the four corners of the globe.

2. (N.Z. prison) the prison riot squad.

[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 78/1: GI Joes n pl. = C and R crew; goon squad, the.
GI shits/trots (n.)

see GIs n.