My silly little (local) example of this is public nudity in Berkeley. The city attorney finally asked the police department to stop arresting naked people because they were wasting time and money not getting the cases to, uh, stick. And everytime people heard about another person getting arrested, 10 more people would show up the next day, all naked as jaybirds. It was funny for a while, but then it kind of grossed me out, because really people: put some clothes on! :-)
/jordan