Benning is a synonym of the word "Fapping". Benning is Fapping, but in public areas, such as bathrooms, classrooms, restaurants, groceries stores, movieplex. It is hardcore meat-beating. So much so that your hand may bruise from said activity.
Guy 1: Dude Did you hear about Lukamar?
Guy 2: No what?
Guy 1: He got caught Benning in the Bathrrom!!!
Guy 2: No way that's hilarious.