Green’s Dictionary of Slang

1. the vagina.

1890–1904

Farmer & Henley Sl. and Its Analogues.

2. a brothel where one might contract venereal disease.

1986–7

Maledicta IX 150: The original argot of prostitution includes some words and phrases which have gained wider currency and some which have not […] clap trap (brothel where you might contract VD).