I'd write a list of everything someone said to me that hurt my feelings and write snappy comebacks that I could drop at a moment's notice to build my confidence.
Example Remark: "Wow. Your head is as shiny as a cue ball. Ha ha."
My Response: "Actually, I use it to blind my opponents while playing pool. It's my super power. Works every time."
If it's a girl who says this to me, I'd choose a flirty response. I'd smile, say the same as above and add, "Let's play. I promise, I won't use all of my super powers against you." (Of course, this means there should be easy access to a pool table.)
If the girl is just being mean to me, I'd say something like, "Oh, you KNOW you want to touch it, but I won't let you," and just walk away smiling.
Anyway, change every joke made at your expense into an opportunity to show that you can both take a joke and dish one out. If you practice, you'll have a sure-fire, split second comeback for most remarks, and you'll feel better about yourself in the long run.
Good luck.