He is probably afraid that his friends will make fun of him for liking you. He is so afraid that he will accidentally show that he likes you, he acts like he dislikes you instead. Men generally do not like to show their true feelings especially in front of other men as they believe this is a sign of weakness. He might also be afraid that you don't like him and doesn't want to embarrass himself. I assume he is quite a young boy (13-16??) - if so he may resort to play-fighting with you. In this way he gets to be close to you and touch you without showing that he likes you. The best thing to do is try to get him on his own and if you like him, tell him. It may be that he doesn't like you at all but I tend to think that if everybody in your social group is telling you he does, he probably does. Good luck!!!