How can I strike up an INTERESTING conversation with people?

I can't talk. Whatsover. Even if I try all fails, and I end up shaking myself inside. Anyways, I have a really good personality (and I'm not just saying this because I'm y'know right here right now) It's because I'm really nice, real, funny, I like to have fun, do crazy sh*t, & HATE fake people. I'm also really caring and I like getting to know people. Thing is, I don't like talking about the usual, boring, conversation topics like weather, school, abortion, nose pain, chest flare ups, whatever, you know all that boring stuff. More like interesting stuff that comes to mind. BUT, I just can't talk. I don't know any funny words to make myself more interesting. I don't know what to talk about if I see an old friend @ the mall (which happens almost everytime). I don't like to be an unintersting, BORING, rat. Oy, help me out? I'm 15!