The duct tape mafia is a gang of counter culture teens who affiliate them selfs with each other via duct tape on them selfs, often the duct tape has D.T.M or designs written on it.
preppy 1-"Why is there duct tape on that guys shoulder"
preppy 2-"Cause I don't know maybe he's mental"
punk 1-"No he's part of the duct tape mafia"
preppy 1 and 2 "what?"