Calling shotgun
In North America, there is a longstanding tradition of determining who gets to sit in the seat next to the driver of a motor vehicle. In order to claim that seat, one must "call shotgun" according to a set of standard rules. The seat next to the driver is called shotgun in remembrance of those men that rode on stage coaches next to the driver with a shotgun to protect the stage from banditos (highwaymen). Or so it's said.
To call shotgun is to, at minimum, yell out "shotgun" while approaching the vehicle. The specific rules are the subject of much heated but good-natured debate, and a number of websites claim to have the official rules.
