Find out who the fucker is and terrorise him(Possibly her)I dont think theres much point in being pissed off about it, rather make my car even better, and the next time the little sh*t sees the car, he can do and cry!
Just have to be aware of where i park in the future. Havent cleaned the car in a month just so the scratch doesnt show too much.
Not really much you can do, just hope this kind of stuff stops....eventually!!