Calling Shotgun is a practice as old as the automobile itself. Older, actually, dating back to the Old West, when a rider would sit with a firearm next to the driver to ward off bandits. That little bit of history may be common knowledge to many, but a whole system of rules and regulations has formed over the years to determine who gets that most coveted of passenger seats, whether in mom and dad's car or when riding with friends.
So the next time you get into a friendly dispute with your traveling mates, you can pull out your own copy of The Official Shotgun Rules Pocket Reference Guide, or study the regs enumerated on the website after the link.
[Source: The Official Shotgun Rules via Holy Kaw! | Image: Chaplin/Getty]