bottom-wetter, n. — Green’s Dictionary of Slang

bottom-wetter n.

[vaginal secretions and semen]

1. sexual intercourse, from the point of view of a woman.

1896

Farmer Vocabula Amatoria (1966) 199: Onction, f. 1. the act of kind; ‘a bottom-wetter’: of women.

2. a penis.

1896

Farmer Vocabula Amatoria (1966) 37: Bidault, m. 1. The penis; ‘the bottom-wetter’.

do a bottom-wetter (v.) (also have…, perform…)

of a woman, to have sexual intercourse.

1890–1904		Farmer & Henley Sl. and Its Analogues.
1980		Maledicta IV:2 (Winter) 182: The tendency [for vaginal fluid to flow] is also remembered in the phrases to [...] to do a wet ’un, to get a wet bottom and to do, have or perform a bottom-wetter, namely to do a turn on one’s back.