Green’s Dictionary of Slang

1. to pursue sexually.

1956		N. Algren Walk on the Wild Side 240: He’ll out-stud any man alive.
2010		A. Steinberg Running the Books 129: I ain’t studdin none of those women.

2. to work as a pimp.

1947

N. Algren Neon Wilderness (1986) 134: Venus told me she pays you off to stud her.

3. to work as a heterosexual male prostitute.

1963

T.I. Rubin Sweet Daddy 113: He does not ‘stud’ and will not be a prostitute.