Older movie, It is about a goth nerd and a group of jocks. Both go to a party fight breaks out. Jocks go and push him in a pool, it turns out empty and the nerd is dead middle finger oddly pointing at his killers. His brain later gets replaced by a sadistic killer. With his new body he goes to a costume party. Jocks at fault kill him with guillotine and with head roles his middle finger goes up once more. Does anyone know this movie?

Big Monster on Campus (2000) (http://www.imdb.com/title/tt0164192/) (aka "Boltneck")