Last night I had my bike tipped over. Well let me tell you I lost it. That is the worst feeling in the world. What kind of person thinks it's funny to tip a bike over. It happened at night of course so there was nothing I could do but if I would have caught them, let's just say they wouldn't even think about tipping another bike ever again.
Payback's easy: find out who it is and tip them over. A leg sweep should do the trick. If he comes up flailing, say 'hey, you did it to my bike, why can't I do it to you?' If he pursues it, take him down. Otherwise he won't learn his lesson and respect bikes/bikers.
If I would have caught them, I probably would have just blatently beaten them to a pulp. If I ever see someone tipping a bike or vandalizing I would get out and make sure they'd never do it again. It's mostly drunk punk kids who think it's funny to knock over a 15,000 bike! Make then feel the pain of koncking it over and ask them if it was worth it.