I have a very basic set of rules in my car. No eating, no beverages without lids, all the basics. I also have a personal pet peeve which is when one window is rolled down, and the other is left up leaving the air no choice but to beat the living crap out of my sensative eardrums.
I have a friend that breaks every single one of these rules seemingly every time he is in my car. Today however he crossed the line putting his leather dress shoes on my dashboard.
The only worse infraction is forgetting to put on your seatbelt, which is punishable by my stopping in the middle of the road refusing to budge until I hear a positive click.
What are the rules you have set in your car?