The difference between me and them?

I am just looking for honest answers please. In the past I have always been the target of being made a fool of or made fun of by the boys. Although, I probably earned it with my smart-*** comments. I am a college student now. I find it odd that young adult men apparently find it amusing to silently snicker while I contribute ocassionally to class discussions. There is nothing awkward or anything that stands out about me that would provoke them. When other girls speak no one says anything. I'm not a show off or "teachers pet", or talk extensively or do any of that stupid bullshit. I just want them to stop and to be taken seriously.