Someone who is being an especially shitty douche-bag.
Jim: "Holy Shit Dan, do you see what that guy is doing with your girl-friend?"
Dan: "Yea. He's being such a Deuce-Bag."
Someone who steals your shit to make themselves look better to others.
Jim: "Jesus Dan. Did John just take your iPhone to show to his girlfriend?"
Dan: "Yea. He's a turd burglar."