be off like a prom dress (in May)

humorous To leave or depart very quickly or suddenly. Likened crassly to the stereotypical quickness or eagerness with which American high school students have sexual intercourse after the prom. Primarily heard in US. I'll have just one more drink, but I've got to be off like a prom dress after that. Jared was off like a prom dress in May once his ex-girlfriend showed up to the party.