rubbing against the edge of a bathtub as a form of masturbation
Person 1: Dude, my friend Spencer told me he rubs himself on a tub to get off!
Person 2: I think that's called tub ledging
The act of rubbing oneself on the side of a tub to get off, a form of masturbation
Person 1: dude what the hell is tub ledging?
Person 2: oh that's a way of jerking off. My friend Spencer does it all the time.