Back in the day when I got picked on, I decked a kid and slammed his face into a gym locker. I got suspended, he got suspended, stitches, and a broke eye socket that required surgery and more stitches. He never said a word to me, tried to do anything, and word got around that I wasn't fun to pick on. I agree with the guys saying for him to stand up to the kid. Screw that "don't throw the first punch" suff as well. Hit him hard, hit him fast, and aim for the chin.