I've always wanted a beanie with two flashing orange lights, so I can put it on and sit on the hood of cars parking illegally while flashing their hazard lights. If they ask/tell me to move, I'll just reply "it's okay, I've got my parking lights on" and remain sitting on the hood for another few minutes. One day.
That's universal. In college I always carried packets of ketchup or mayo to put on car door handles when people left their cars unattended in no parking zones. 4 ways on, of course.