Green’s Dictionary of Slang

1. a bug.

1909

‘O. Henry’ Roads of Destiny 350: I had to sleep on it, and drink water with little zoos in it; so, of course, I got the Chagres fever.

2. a prison; a brothel whose workers come from ‘all nations’.

1927		‘Jargon of the Und.’ in DN V 467: zoo, (1) A jail. (2) A brothel made up of prostitutes of many nationalities.
1931		Irwin Amer. Tramp and Und. Sl. 198: Zoo.– A prison or jail. A ‘house of all nations’ or brothel whose inmates are from many lands and places.
1962		Ragen & Finston World’s Toughest Prison 823: zoo – A prison or jail.
1966		F. Elli Riot (1967) 5: I’ve been in this zoo over four years on a lousy beer-joint burglary.
1989		J. Morton Lowspeak.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 206/2: zoo, the n. prison from the variety of ‘Society’s wild beasts’ there compounded.

3. (US campus) a rowdy, aggressive event, a wild party; thus as v., to be noisy and rowdy.

1964		in Current Sl. (1967) I:4 5/2: Zoo, n. Place where students congregate.
1975		Spradley & Mann Cocktail Waitress 61: A party could be a zoo.
1985		K. Vacha Quiet Fire 168: One of the guys I knew who went told me it was just like a zoo with all the transvestites and such.
2022		A. Kirzman Giuliani 175: A Giuliani trip anywhere was always a zoo; his aides were noisy, sleep-deprived, and self-important.

4. (US) a police station.

1975

L. Dills CB Slanguage.

5. (US teen) a gathering place, i.e. a street corner.

1987

Arizona Dly Star (Tucson, AZ) Youth Beat 26 Dec. 8/4: Zoo: Street corner.

6. in personifications [the senses suggest antithetical images of such a place].