Green’s Dictionary of Slang

pimple n.²

1. the head.

1811		Lex. Balatronicum.
1821		W.T. Moncrieff Tom and Jerry III i: Aye, aye, be leary, Bob, take care of your ribs – mind your pipkin – be down on your pimple.
1832		Egan Bk of Sports 158: Ramming his pimple into Lalla’s bowel-box.
1842		Flash (N.Y.) 10 July 2/2: Lilly got a pretty hard one on the pimple, dodged another and [...] planted a severe facer.
1845		J. Lindridge Sixteen-String Jack 83: As snug a snuggery as any single gentleman need wish to shove his snug old pimple into!
1855		(con. 1837) Fights for the Championship 356: Swift [...] planted his left and right on the Jew’s pimple.
1857		Bell’s Life in Victoria (Melbourne) 16 May 4/4: Mace [...] administered the left and right [...] on Master Bill’s damaged pimple.
1859		Wkly Varieties (Boston, MA) 3 Sept. 6/1: Joe Sandford had better leave off stealing from his companions, or he will jeopardize his pimple.
1860		Bell’s Life in London 2 Dec. 6/3: King [...] administered a right-hander on the side of the pimple.
1861		Bell’s Life in Sydney 2 Mar. 3/3: A ‘pimple’ was thrust from an upper window and a melodramatic voice demanded ‘what’s up’.
1867		Wrexham Advertiser 2 Mar. 7/1: In the language of the prize-ring [...] a man has not a head, but a ‘nut,’ or ‘pimple’.
1908		Leigh & Powell [perf. Marie Lloyd] Rum-tiddley-um-tum-tay! 🎵 ‘Straight! they must be simple, / Or touched in the pimple!’.
1922		Collins & Leigh [perf. Hary Champion] ‘Everybody knows me in my old brown hat’ 🎵 Everybody knows me in my old brown hat / That I’ve got upon my pim-pim-pimple.
1938		D. Runyon ‘A Job for the Macarone’ in Runyon on Broadway (1954) 691: It finally becomes necessary for Charles to tap him on the pimple with a beer mallet.
1944		D. Runyon Runyon à la Carte 37: I quietly give Girondel a boff over his pimple.

2. a baby’s penis.

1984

Partridge DSUE (8th edn) 884/2: late C.19–20.

3. (US) a fool.

1988

H. Gould Double Bang 142: ‘Everything okay, Frankie?’ ‘And what are you gonna do if it’s not, you guinea pimple.’.

In compounds

pimple audience (n.)

(US) the teenage audience.

1965		Courier-Post (Camden, NJ) 11 Mar. 38/7: Their high-raged [sic] ‘pimple audience’ shows.
1966		C. Keil Urban Blues 78: [T]he nine- to sixteen-year-old age group, the same ‘pimple audience’ who have rapidly become the final arbiter of the nation’s tastes and fashions in many other areas.

pimple cover (n.) (also pimple coverer)

a hat.

1825		Pierce Egan’s Life in London 2 Jan. 389/1: The Black Diamond first threw his pimple coverer into the ring.
1830		Egan Finish to the Adventures of Tom and Jerry (1889) 309: I give and bequeath unto my friend, Jerry Hawthorn, Esq., my tile, my castor, my topper, my upper-crust, my pimple coverer, otherwise my hat.

In phrases

like a pimple on a cow’s arse (also like a pimple on a pumpkin)

utterly insignificant.

1949		J.H. Burns Lucifer with a Book 140: I called the little squealer the pimple on the arse of the school.
1961		(con. early 1950s) J. Peacock Valhalla 401: ‘Some fuckin’ Tanker was mouthing off.’ [...] And Dallas tole him, ‘You wouldn’t make a pimple on my ass.’.
2003		McGill Reed Dict. of N.Z. Sl. 127: like a pimple on a pumpkin Insignificant. ANZ.