I don't put myself down because i know that this is all true but i think that i am one UGLY SON OF A B*TCH! lol and i know that i can't get a girl whatsoever because ever girl i asked out, rejected me. I know that i am also half mentally challenged. At least that is what i think. I dont get mad or offended when my friends or anybody call me these things because i know that it is all true and i start to laugh when they make fun of it. IIN to think this way about yourself?

about asking girls out, i hope you are looking at girls who you would consider similar to you. in other words, don't aim for ms. popular, not right now anway.
if you really think you have some sort of disability, i strongly urge you to talk to someone you know is mature and intelligent. i am thinking on the lines of school counselor, trusted teacher, etc.
depending on your age, this could just be adolescence issue, or puberty type difficulties. good luck
one thing for sure, this is a temporary problem and you should grow out of it.
When you are confident people will respect you for it. Same with girls, girls mostly only date confident people.
Remember you are as wonderful as you think you are, and your friends probably see the insulting and such as a joke and because you laugh that just proves to them you can take their jokes (which you don't) just tell them how you feel (without getting too emotional).