Cut him open..
No seriously this is a normal period in every man's life,and you got to go trough it,it's up to you how you gonna solve it.
Each and everyone of us was in this situation some way, only differences is how you put you're self to them from the start.
In my case when I was younger and I felt that shit coming in, I anticipated it,so I show my teeth to them,showed them that Im not scared and from that moment I never had a problem with anyone,I even became friends with some of them.
In that case its a bit to late to do that,since they felt that they can bully you around and go trough with it,but you still got options.
Calling principle,parents,
police.... come on,be a man and stand for you're self because this process is gonna last to long anyway,and you gonna get laugh at for doing so afterwards.
What ever you do you need to be two steps ahead,if you whana smash his fucking face off you need a good plan same thing goes for the diplomatic way that some people here propagate,but I would go for option A,since this so called bully is probably young and you cant put any since in to him with words and punishments.
Or just get fat and do what he did
bully gets owned buy fat kid need to watchUnleash the devil:cool: