A good ear popping whack side of the head would have stopped the little tyrant.
How do you all know that this kid isn't being beat silly at home? You just assume he isn't being disciplined, as if a disciplined child never does anything wrong.
I can tell you from my experience as a substitute teacher -- I was watching from my window at a child being beat all the way into school by his mom. Yeppers, right into my class! And right back out again as he tried to take his rage out in my class. Sometimes things are a sorry state of affairs for kids.
I do agree that the bottom line is the parents. But I also know that children are separate beings from their parents and sometimes act accordingly. They manage somehow to embarrass us, or completely forget how they were raised.