Green’s Dictionary of Slang

1. the anus.

1999–2004

UrbanDictionary.com 🌐 Stench Trench. someones unwashed arsehole. [...] a vagina in need of a wash.

2. the vagina.

1997		Roger’s Profanisaurus in Viz 87 Dec. n.p.: stench trench disaffectionate euph. Fanny.
1999–2004		see sense 1.