i can't not be friends with her?

[dare ~ girl]

okay, so this girl that i don't like, i can't not be friends with her-she keeps on hanging around with me.
i'm not saying she's a bad person, we don't get along because:
people call her nicknames in class and she just stands up and shouts really loud 'MY NAME'S NOT _____' whatever it happens to be at the time.
in class she laughs at stuff that isn't even funny-nobody else finds it funny, and her laugh is super loud (although her laugh isn't her fault) but i don't think she actually finds it funny because she stops instantly when a teacher looks at her.
she takes things WAY too far, like if we're playing dares or just messing around and she goes all over the top.

but i have tried alot of ways to let her know i don't want to hang out with her-but she doesn't get it. if i just tell her straight she'll go to the head and say 'miss she said she hates me and is being mean to me'. help me get the message across to her?