Green’s Dictionary of Slang

(US campus) one who makes themselves available for sexual intercourse.

1989		P. Munro Sl. U.
1997		K. Kainulainen ‘University Euphemisms in Calif. Today’ 🌐 A very noble-sounding ‘donor’ is a person who makes himself available for sexual intercourse, and scientific ‘Einstein’ means ‘pubic hair’.