Guy's Behavior

A guy grabs my butt at school not in a relationship or really good friends?

So I'm 15 and there's a new guy this year. We don't have any classes together execpt for sharing a P.E. period together. He makes many girls laugh w/ his semi jerky comments but we always laugh. And I can't tell if I'm different. He always says stuff to me and how blah blah is my boyfriend or how should date so and so. He does make laugh a lot though some times its kind of mean but I can't help but laughing. For like 2 weeks straight he told me I had no butt. And when we came back from winter break he even remembered and continued telling me I have no butt. One he ran up to me when we were walking to gym class in the morning he told me "no ass not even in leggings" so I said (saving this comeback for weeks) "well if your looking I must be doing something right" he smirked . And unexpectedly his hand grabbed my ass! I walked away shock heading straight for the girls locker room. All I did was turn around and looked at him with a very shocked face. a lot of my friends got down on me because I didn't do anything about it. The guy didn't seem to be phased at all but I was. A couple weeks later i feel like he was using any reason to touch but no in anyway innapropriate. I would even say were friends so what does this mean.
A guy grabs my butt at school not in a relationship or really good friends?
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