A quote
made famous for its use in season 1 of Supernatural. Implies that the driver of a vehicle chooses what music they and the passengers
will listen to while whoever is riding shotgun must stay quiet.
Sam: You gotta update your music collection. Black Sabbath? Motorhead?
Metallica? It's the greatest hits of
mullet rock.
Dean: Well, house rules Sammy. Driver picks the music, shotgun shuts his cakehole