A Bluetooth hands-free headset. Mainly applies when the user is in a public place having a conversation on the phone loud enough for people ten feet away to hear and that said people ten feet away do not wish to hear.
Person 1: Is that dude talking to himself?
Person 2: Nah, he's got his d-bag tag in his ear.Douchebag
with a d-bag tag on: So I told him I wanted those accounts closed out by 3 p.m. and the bastard went out golfing instead...
Cashier: (thinking) Man I wish this bastard would get off his d-bag tag long enough to get the hell out of my line.