The Loved Ones (2009)

As the school formal approaches and decisions are made about what to wear and who to go with, Lola Stone, the quietest girl in school, asks her secret love Brent to go with her. But Brent is already going with his girlfriend, Holly. Upset with the rejection and with the formal only hours away, Lola and her father plan for Brent to be with her regardless. But it's not the school formal, it's a demented, sadistic and exclusive party hosted by Lola and her father - where the entertainment is Brent himself.