Why is this guy mean to me but is very nice to my female clmate?

I am ok if he doesn't like me. I just don't like that he is teasing and making fun of me. I understand he thinks he is smart and that is why he is a "graduate student" and the other clmate. I just don't understand why he is rude to me. I am an undergrad and I am in the same graduate cles as he is but so what? If he didn't like me he show ignore me, not touching my school supplies or annoy me by closing my laptop when I using it. I don't understand why he dislikes me? I can't imagine he would jealous either. He is just cynical and sarcastic. I need perspective from others. What is his problem?