Someone who gives out lots of unprotected blowjobs.
Person One: "Did you hear that Caitlyn gave a blowjob to five guys last night?"
Person Two: Damn, what a herpe slurpee!"
An oral herpe breakout makeout session.
Guy 1: "How was your date with Elizabeth?"
Guy 2: "I was kinda nervous cause of this herpe on my lip, but she had one too, so we made out all night anyway..."
Guy 1: "Ew, total herpe slurpee!"