My take away from that story is that if you're unhappy with yourself, you should work to change what you don't like. People would tease you if you picked your nose and ate boogers. Should we accept that behavior? Obviously not. Kids teasing each other helps promote social norms. Yes sometimes it's wrong and cruel (toward things that can't be helped, like disabilities and whatnot), but in these cases it serves a purpose, whether they want to admit it or not.