A unit of measurement originally based on sections of the hand, is now most commonly associated with the penis and/or the surrounding area. It is equivalent to 6 inches, 1.5 hands, or two palms.
Guy 1: Hey, do you see that guy over there?
Guy 2: Yeah, what about him?
Guy 1: Lot's of chicks have said that he's got a two shaftments long package.