Green’s Dictionary of Slang

hot-on n.

[hot adj. (1a)]

1. (US black) lust; lustful feelings.

[US]C. Himes Blind Man with a Pistol (1971) 58: You ever see Madame Thomasina wih a hot on for whitey.

2. (US campus) an unpleasant person.

[US]Baker et al. CUSS.