Just walk away from the bully. That makes them really mad. Or, for instance, if they say that you are stupid, say "Yes I am!" then they can go along insulting you but if you just say "Yup" or just any form of agreement then they can get really mad because you are not reacting to them. That's what I do. Half the people at my school dislike me. Eventually the bully will just leave you alone and pick on someone else. Also, for being "cool" can sometimes be bad. I, personally, get good grades and have friends that get good grades, and the kids that others consider "cool" are the kids who get D's and F's, and I would not want to be that kind of person. Just get your group of friends and hang out with them. I have like 5 friends, and I think that is fine.