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Section I - General Rules of Calling "Shotgun"
1) The first person to yell "SHOTGUN" gets to ride in the front seat.
2) The remaining back seats may be divvied up in the same manner by being the first to call "back right seat", etc..
3) The word "shotgun" must be loud enough to be heard by at least one witness. If no witness is to be found, or in case of a tie, the driver has the final word. After all, it is most likely his car. (note: if it isn't his car, and the owner is present, the owner's decision is final. Owner must be sober, however, or he will defer his judgment to the driver.)
4) Early calls are strictly prohibited. All occupants of the vehicle (including the driver) must be outside of the building and directly on the way to the vehicle before shotgun may be called. Under no circumstances may a person call shotgun inside a building. For sake of simplicity, a garage is considered to be outside. Parking structures and detached garages are always considered as being outdoors, even if they are underground.
5) A person may only call shotgun for one way of a trip. Shotgun can never be called while inside a vehicle or still technically on the way to the first location. For example, one can not get out of a vehicle and call Shotgun for the return journey.
6) Being as how everyone is created equal, men have the same right as women to the front seat of the car. i.e. women don't own the front seat.
7) One is allowed to ride shotgun as many times as he can call it, but for himself only. No one can call shotgun for their slower friend, unless the friend has a speech or mental handicap that prevents them from calling it for themselves.
8) The driver has final say in all ties and disputes. The driver has the right to suspend or remove all shotgun privileges from one or more persons.

Section II - Special Cases of Calling "Shotgun"
These special exceptions to the rules above should be considered in the order presented; the case listed first will take precedence over any of the cases beneath it, when applicable.
1) In the instance that the normal driver of a vehicle is drunk or otherwise unable to perform their duties as driver, then he/she is automatically given Shotgun.
2) If the instance that the person who actually owns the vehicle is not driving, then he/she is automatically given Shotgun, unless they decline.
3) In the instance the driver's spouse, lover, partner, or hired prostitute for the evening is going to accompany the group, he/she is automatically given Shotgun, unless they decline.
4) In the instance that one of the passengers may become so ill during the course of the journey that the other occupants feel he/she will toss their cookies, then the ill person should be given Shotgun to make appropriate use of the window.
5) In the instance that only one person knows how to get to a given location and this person is not the driver, then as the designated navigator for the group they automatically get Shotgun, unless they decline.
6) In the instance that one of the occupants is too wide or tall to fit comfortably in the back seat, then the driver may show mercy and award Shotgun to the genetic misfit. Alternatively, the driver and other passengers may continually taunt the poor fellow as they make a three hour trip with him crammed in the back.