How do you make a bully shut up!!!?

Okay, so i'm a new kid at my school, so far i've gotten nothing under an 85%, i have plenty of friends and have created my own little (clique), but the only thing I CAN'T STAND, is my History cl!!!, I'm forced to sit next to this fat kid, who makes fun of EVERYTHING I DO!, if I blink he mimicks me, if I laugh he mimicks me, if I talk he makes fun of my voice!!!!!, now I know what your thinking, he's fat, why not tell him he's fat, (keep in mind that, i'm in school, and cracking disses like that get's me a one way ticket to the principal's office), i'm not going that far until he makes fun of my race, or religion.....he sits at my table, is in EVERY CL I HAVE!!!!, and even my homeroom, WHAT DO I DO TO SHUT HIM UP?!, I NEVER know what to say when he disses me!, what do I do?????,( and please don't give me any "ignore him", or "tell your parents" crap, I did that at my last school and look where I am?", I want to DISS!!!, what do I say????