Gutterballs

After two adversarial groups of teenagers clash at a bowling alley during its midnight disco party, one of the girls is violently raped. The next night, all the kids return for a revenge session but are surprised to encounter a homicidal stranger. Wearing a bowling bag on his head to disguise his identity, the killer begins picking off the teens one at a time, making sure each experiences a grisly death in this gory slasher flick.