Green’s Dictionary of Slang

keister n.

also keaster, keester, keyster, kiester, kister
[Ger. kiste, a box, a case + Ger. sl. the rump]

1. [late 19C+] (US) a suitcase, a satchel, a handbag, a salesman’s sample case.

2. [late 19C+] (US Und.) a burglar’s bag of safe- or house-breaking tools.

3. [1910s+] (US Und.) a safe, a strongbox (often within a safe).

4. [1930s–40s] (US) the female genitals.

5. [1930s+] (orig. US) the anus, the buttocks.

6. [1940s–60s] (US) a prison.

7. [1960s+] (US) one’s self.

In compounds

keister bandit (n.) [-bandit sfx (2)]

[1930s+] (US prison) a ‘masculine’ male homosexual; by ext., a womanizer, a rapist.

keister bunny (n.)

[1990s+] (US prison) an inmate who places contraband items – tobacco, drugs – in his rectum.

keisterman (n.)

[1930s–50s] (US Und.) a thief who specializes in stealing suitcases on railway stations.

keister plant (n.) [plant n. (20)]

[1930s–70s] (US drugs) a cache of drugs hidden, usu. in some form of hollow metal container, in the rectum .

keister shafting (n.) [shaft v. (1)]

[1980s+] (US gay) anal intercourse.

keister stab (v.) [stab v.]

[1980s+] (US gay) to have anal intercourse.

keister stash (n.) [stash n.1 ]

[1960s] (US Und.) any slim, hollow item, e.g. a biro tube, that can be placed in the anus and used to transport money, drugs etc.

keister-stashed (adj.)

[1960s] (US prison) hidden in the anus.

In phrases

grease someone’s keister (v.)

[2000s] (US) to sodomize.

In exclamations