If some jerk-off who you don't even know calls you a pussy, don't take it so seriously. He's an asshole and fucking his shit up isn't going to change him for the better. If you really want to be happy, just stay away from negative people like that. Violence is only justified if you're using it for self-defense or fighting for your freedom. Seeing as how he is not a real threat to you and is not taking your freedoms away, it's best just to just ignore the fucker and get on with your life.