A Cock brand, sometimes refered to as Cock Logo is a tattoo, most commonly of tribal design, appearing on the backs and shoulders of Cocks, douches, and other social retards and serve as a good mark of who to avoid in the bar.
Person1: Dude I'm gonna get a tattoo!
Friend: Cool what kind?
P1: A tribal right here on my shoulder! it'll be awesome
F: No it'll be a cock brand and you'll look like a douche!