Leaving the scene of a sexual encounter before one's partner has had a chance to clean up. (specifically/crudely: while things are still dribbling out of things)
He was a total asshole. Pumped me full of seed and pulled a French exitquicker than you could say 'je ne sais quois.'
John brought a bottle of pink mosacto and performed a French Exit at Zach's party and now Zach and Sarah are getting a divorce. Fuck John, but not in the way Sarah did.