Sick Girl

Sick Girl is a 2007 American independent horror film written and directed by Eben McGarr.

Izzy is raising her younger brother, Kevin, by herself. Their parents are deceased and her older brother, Rusty, is away in the Marines. When Izzy learns that her little brother is being bullied at school, she does what any unstable, psychopathic, homicidal sister would do.The movie starts out with Izzy waiting for the school bus. In the back are two popular girls who make several snide remarks about her. One of the girls boyfriend is following the bus route in his car with his friend. The girls drop a pair of panties out the window, and if her boyfriend finds them, hell be rewarded. ........

Source: Wikipedia