Either through misleading or physical force, getting someone to high five you for something they would normally not five you for.
Guy 1: High five for a drunken awkward threesome with your step sister!
Guy 2: Wait, what?
Guy 1: Every night for the last three weeks I've been rubbing my wang on your toothbrush!
Guy 2: *Shocked*
Guy 1: *Walks over and slaps the stunned man's hand*
Guy 3: Dude, way to Five Rape.