Coney Island, n. — Green’s Dictionary of Slang

Coney Island n.

[ironic use of the place name, Coney Island, New York’s leisure centre]

(US prison/Und.) the room used by police for interrogation.

1931		G. Milburn ‘Convicts’ Jargon’ in AS VI:6 437: Coney Island, n. A room used by police for the third degree.
1949		Monteleone Criminal Sl. (rev. edn).
1950		Goldin et al. DAUL 47/2: Coney Island. The police-station chamber in which subjects are questioned or given the third degree. ‘The bulls (police) took him down to Coney Island, kicked in his cruller (beat him severely) and made him come through (confess).’.

Proper name in slang uses

In compounds

Coney Island chicken (n.)

a spiced, heated sausage or frankfurter, esp. when served in a bun with fried onions, chili sauce and mustard.

1933		W. Winchell On Broadway 10 Oct. [synd. col.] When the first half of the 2nd game was dull I got a laugh out of a flip-crackling hot-dog vendor, who kept yelling: ‘Here ya are! Get ya hot franks – better known as Coney Island chicken!’.
1936		H.W. Bentley ‘Linguistic Concoctions of the Soda Jerker’ in AS XI:1 42: CONEY ISLAND BLOODHOUNDS. Frankfurters. CONEY ISLAND CHICKEN. Frankfurter sandwich.

Coney Island (head) (n.) [the way visitors were defrauded by the bartenders of Coney Island]

(US) a beer that has more frothy head than actual beer.

1960, 1975		Wentworth & Flexner DAS.
1993		(ref. to late 19C) I.L. Allen City in Sl. (1995) 10 2: The public learned once again that ‘you get what you pay for.’ This is the pejorative idea behind the name Coney Island for a glass of beer with much foam and little beer. The offensively large head itself was called a Coney-Island head.

Coney Island whitefish (n.) (also Canarsie whitefish) [the popularity with lovers of the beaches of New York’s Coney Island; similarly used of the beachfront at Canarsie, N.Y.]

(US) a used contraceptive floating at the edge of the beach; but note alternative suggestion in cite 2010.

1988		H. Gould Double Bang 27: They washed up at the doors of the River Royale like Coney Island whitefish on a Sunday morning.
1993		(ref. to 1930s) I.L. Allen City in Sl. (1995) 10 2: Coney Island also gave its name, probably in the 1930s, to the Coney-Island whitefish, a used condom floating in the water at the bathing beach – a common sight then and now.
2000		www.sbermprod.com 🌐 Whitefish (Drums) He eats a lot and smells a lot, but he’s a true-blooded pirate. Named after the ‘Coney Island Whitefish’ (a used rubber).
2004		E. Miller ‘Practicing’ in Brooklyn Noir 95: Jamaica Bay’s increasing population of Canarsie White Fish – floating used condoms.
2008		T. Dorsey Atomic Lobster 175: Toilet got so clogged with Coney island whitefish we had the plumber on speed dial.
2010		Codella and Bennett Alphaville (2011) 131: ‘Coney Island whitefish’, slang for a used condom, didn’t derive from the consoms that wash ashore at the beach, it came from the fact that used condoms tossed out of the windows of the projects [...] bloated and burst in the sun just like their namesake would if they were beached on hot pavement.