Green’s Dictionary of Slang

(US gay) a (heterosexual) male who attracts homosexual men; one who makes an effort to attract such men.

1974		J. Lahr Hot to Trot 17: He wears no underwear under those hip huggers. Bum-boy. Fag-bait.
1987		Nat. Lampoon Dec. 26: ‘Is there anyone who doesn’t think Ralph [...] is fag-bait?’.