A chin beard, usually short and well-groomed, that is purposely shaved into the shape of a triangle pointing towards one's lower lip, with no other hair on the person's face (mustache, sideburns, etc.) The name comes from the fact that a person who has it is usually a douchebag.
Person 1: Wow, that fucker just flipped me off! Is 50 in a 40 zone not fast enough for him?
Person 2: Doesn't surprise me, he's got the douchebag triangle.