What should I do about this girl?

Hey what should I do about this girl? At school I have 2 best friends. I really like them both, and their really nice. We had a lot of fun together but one day, this weird looking unpopular girl started following me around. I REALLY don't like her, she is super weird and annoying. Like, she likes Tummie ham, and she always says TUMMIE HAM IS YUMMY IN UR TUMMIE, and one time I was sitting on the bleachers, then she put her head on my lap, and then she sniffed me u know where. :( Which really freaked me out. The problem is is that she is SUPER clingy. First she just followed me, but now somehow she made friends with my best friends and now their friends with her. It really makes me mad! I am not kidding, she makes me feel bad just looking at her! Everytime I look at her, she makes me feel sad. Like these negative vibes. How can I get rid of her without making my best friends sad?