Why am I getting picked on because I'm not sex obsessed?

A lot of young people are VERY insecure about sex, and they do obsess about it because everyone else seems to be sexually active and having a MUCH better time than they are. A lot of the kids who are active are not actually all that happy with it, they're doing it to be part of the group. And some are lying about it.

When they see someone who is not having sex and not frantically seeking a sexual partner, it makes them question whether they are doing the right thing. Instead of thinking about their own choices, it's easier to pick on the person who they perceive is making them uncomfortable.

As "Hell" says, find some different friends. People who try to force you to be like them so they feel comfortable are not your friends. They are sheep.

It's because they think you're an homosexual, obviously.

Find new people to be around. I would call it immature, but it's such a stupid thing to be 'made fun of' so why even care?

You're not really explaining what you mean by not being obsesses with sex. Most people AREN'T. In order for anyone to give you an accurate response more information would be needed. And not being interested in sex at all or not finding it enjoyable may be a problem either physical or not being in touch with what you like sexually or how to get there. But regardless of that no one has the right to judge you based on something as private as that but than again in order for someone to judge you on it you must've told them about it your sex life. To avoid judgement on something private like that refrain from discussing something so personal and no one will critique you