Bully - by Larry Clark (2001)

Based on a true story. Naive teenagers plot to murder one of their own, who has been too much of a bully to them.

After finding himself at the constant abuse of his best friend, Bobby, Marty has become fed up with his friend's twisted ways. His girlfriend, a victim of Bobby's often cruel ways, couldn't agree more and they strategize murdering Bobby, with a group of willing and unwilling participants in a small Florida town. In the midst of their plotting, they find themselves contemplating with the possible aftermath of what could happen.