Awww.
That happened to me the other day, sometimes people are a bit mean to me.
My friends also noticed and just kept asking me what was the matter. When I eventually told them why I was unhappy they told me to feel a bit happier, for they are my friends and would always try to give me the 'minimal' help and maybe to mention it to a teacher.
OK, maybe if they'd said "maximum" help then I would've liked it more, but it made me happier.
If people are being mean to you, but they are not your friends, don't let it get to you.
Don't bottle your feelings either. I don't mean you explode to the people that are being mean to you. Tell your friends. Let it out to someone, and I imagine most people are more comfortable round these ages telling their friends than maybe parents/teachers although equally recommendable.
I am sure your friends will understand and listen and will try to help you out, or at least make you feel better when you are with them.
Another attitude you can take is perhaps, next time someone jokes at you in a mean way, just don't demonstrate you took it as offense, or that you like it. One of the stupider ones in my class decided to make fun of the way my hair was, like "Haha, you have a palm tree on your head" so I just said "Well, I like it that way *smile*". If you don't let it sadden you they can't do anything else. In fact, in the end he ended up saying "Ok ok, yes, it's cool. In fact, there is someone on TV who wears it like that." And then I just to make sure "And don't laugh at me again". "Ok, ok". And that was the last from him about my hair. =]