I had this happen, someone backed outta their parking spot into the bed of my truck once. Put a dent, which I didnt notice until I got home, but its kinda visable... But I let her go... Cause we are in High School, and its only like a $3000 truck, so nothing fancy, so a little dent didnt bother me... And I didnt let her go cause she is like the hottest girl in the school! lol. It did more damage to her car too.
Today was april fools day, so I was thinking about putting a note somewhere on her car saying, "This is for Hitting me!" and then either doing nothing, or sprinkling suger around the gas cap, but not in the tank, lol. But I didnt....
I tried the balloon over the exhaust on one of my friends, but the balloon wouldnt fit, lol.