Green’s Dictionary of Slang

peehole n.

also P hole
[pee n.1 (1)]

(US) the vagina.

[UK]A. Crowley Snowdrops from a Curate’s Garden 35: [He] let us have the news, which when read seemed as bald and colourless as the pee-hole of an albino baby.
[US]‘J.M. Hall’ Anecdota Americana II 17: All this time I’ve been looking in de P hole and now I’ll haff to start looking in de S hole.
[US] ‘Betty Co-Ed’ [comic strip] in B. Adelman Tijuana Bibles (1997) 57: I still prefer the old pee hole.
[US]C. Bukowski Erections, Ejaculations etc. 112: She also hinted that she wouldn’t mind showing me a little peehole herself.
[US](con. 1910s) F.M. Davis Livin’ the Blues 36: A woman had a ‘pussy,’ ‘peehole,’ ‘poontang,’ ‘sack-a-madam,’ or ‘booty’.

In compounds

peehole pirate (n.)

(US) a rapist.

[US]M. Braly On the Yard (2002) 6: ‘You’re some peehole pirate,’ she said pleasantly.