I had an Egg thrown at my Camaro a few weeks back.

Unfortunately part of the egg had already dried on the rear bumper of my car.It left a "defect" in the paint,but not too noticeable unless you look really close(IBM Blue),yeah you could say i was really pissed off!

But what can ya do?Unless you actually see the punk(s)who did it,you can't do anything except maybe put a car cover over your car,or hopefully if you have a garage,but i don't.