Green’s Dictionary of Slang

indulging in lesbian sex; also as adj., lesbian.

1921		Lichtenstein & Werner Medical Rev. of Reviews in Katz Gay/Lesbian Almanac (1983) 402: She had indulged in the practice of ‘bull-diking’.
1928		C. McKay Home to Harlem 36: And there is two things in Harlem I don’t understand / It is a bulldycking woman and a faggotty man.
1931		N. Van Patten ‘Vocab. of the Amer. Negro’ in AS VII:1 27: bulldycking. M. adj. Lesbian.
1961		C. Himes Pinktoes (1989) 17: Them is fairy cats, or else they is bulldiking.
1971		R.D. Pharr S.R.O. (1998) 388: ‘Are you trying to tell me that [...] you’re only going to go in for bulldiking?’.
1994		Sapphire ‘A Window Opens’ 🌐 I wonder what all this has been for / the women I hid in and could not love, the lesbian front / that became a wall, the sex work. It is clear / I was not cut out for bulldyking or prostitution now.