Help with this girl?

Okay, "this girl" is cousins with my bestfriend. the problem is, she gets picked on and hates it. but, she gets picked on because she attracts the wrong kind of attention. She blurts out things in cl such as "Pixie!!" and she says China poisons people [no comment on that, please]. She is OVERLY obsessed with anime. its all she talks about. she makes videos on gay anime characters [again, no comment]. She talks to herself,and takes it offensive when people tell her to shutup. like in cl, she'll go, "OMG, why am i getting youtube messages during school" and today in homeroom goes, "YES HE REPLIED" everyone stares at her and laughs. the real problem is, she acts like shes in preschool, and she is completely unaware of the realtiy of highschool. her world is in her cartoons. So, how can my bff and I convince her to grow up and that cartoons are a hobby, not a part of life?