Green’s Dictionary of Slang

(US) genital herpes.

1978		University Tennessee student n.p.: Guess who’s got the herp? [HDAS].
2002		‘An Essential Reader’s Guide To Manly Chick LIving’, 16 May,‘Wicked-Sezzy’ 🌐 Said, usually while making fun of Uglybutt, as shorthand for ‘Herpes’. For example, Saturday morning, Jenny was going on about how retarded she felt about her actions the night before, and so I said ‘Well you should ya dirty ho, you probably picked up the herp!’.