Someone who has way surpassed the levels of douchebag, fucker or motherfucker. Partially derived from Cleft denoting a birth defect. A Kleffbag is the mother of all assholes, a level at which can only be reached from a severe mental birth defect.
I heard he was a real asshole, but I'd say he's more of a kleffbag
by GRBrewsday January 23, 2011