Love the idea of mailing trash back to the folks that generated it! I'd get a kick out of dropping the trash on their doorstep myself!
Those that litter really irritate me, even from a young age. As a teenager (many decades ago), me and my friends would go party in the desert. If a friend decided to chuck trash out the window while I was driving, I'd slam on the brakes and make him or her go pick it up. If they put up any resistance, they would find themselves having a long walk home. Not one bottle or can was ever left behind!
A group I belong to adopted a stretch of freeway and performs clean-up events a couple times a year. The amount of trash picked-up is always shocking.
Problem is, nobody feels like they should be held accountable for their actions these days. Quite sad!