Green’s Dictionary of Slang

(gay) the vagina.

1962		R. Hauser Homosexual Society Appendix 3 167: Mute, vagina.
1972		B. Rodgers Queens’ Vernacular 140: mute (Brit gay sl) the vagina.
1982		Maledicta VI:1+2 (Summer/Winter) 139: With the caveat that Hauser can’t spell, we can notice these lesbian terms: mute (vagina), jubes (breasts), polonehomi (actually omi-palome) for ‘Lesbians’.