The Devil's Lettuce

When a group of friends party in a graveyard on Friday the 13th one of them gets too drunk and breaks the only bowl they brought. Trying to keep the party going Bud finds a human skull and shows it can be smoked out of. After the guys smoke out of the skull something happens. Their eyes change. They start getting animalistic and aggressive, scaring the ladies. The women are forced to run for their lives from their own friends. Are the men possessed or are they sick?