Biggest problem I seem to have is coworkers throwing their food wrappers, empty bottles and various junk in the bed of my truck.
And it seems I'm not alone. Don't ask me why, but some people are just so inconsiderate of others that they feel it's their right to be able to throw their junk into other people's cars. My coworker has a vw bug he cut the top off, and pretty much every day he finds different junk in there.