Idle Hands

Mr. and Mrs. Tobias are settling into bed when they notice a message on the ceiling claiming someone is under the bed. They hear a noise from outside and as Mr. Tobias goes to check what the noise was, Mrs. Tobias calls the police, but she gets dragged under the bed and killed.
Anton, their lazy stoner son, hasn't noticed their disappearance in seven days. One morning, Anton runs out of weed and goes to his friend Pnub's house to get some more, but he says he's run out of weed too. Pnub and his other friend Mick suggest that Anton should go and talk to his neighbor Molly, the girl that he likes. He sees that Molly dropped her lyrics book and goes to return it, but he ends up being awkward and fleeing her porch.
Meanwhile, a druidic high priestess named Debi LeCure is hunting the spirit responsible for killings across the country. She seems very passionate and determined to stop the evil hand and races to Anton’s town upon hearing about the murders. As Anton is returning from shopping, he’s stopped by two young police officers he used to go to school with. They search and bust him for having an empty baggie on him and littering after one of the cops drops it on the ground. Anton goes home and smokes oregano and nutmeg using the cite as rolling papers. Realizing that was a mistake, he goes to the kitchen to wash his mouth out and makes himself a sandwich. When going to spread mayonnaise on it, the knife he’s using is covered in blood and his cat Bones is playing with an eyeball. Running in a panic, he trips and finds his parents' corpses.
Mick and Pnub show up and Anton shows them the bodies, then they figure out that Anton is the killer. Mick tries to call 911, but Anton pulls out the phone cord and claims that he isn't the killer, but he murders Mick with a glass bottle. Anton promises Pnub that he didn't mean to do it, but they find out that Anton's hand is possessed. His hand chases Pnub into the basement and tries to stop his hand so Pnub can escape, but his hand overpowers him and decapitates Pnub. Anton's hand throws Bones out the window and he goes to look for him, but the hand pulls him onto Molly's porch and rings her doorbell. Molly takes Anton into her room to make out, but her parents come home so Anton leaves. Anton buries his friends' and parents' corpses in his backyard, but Mick and Pnub come back as zombies and knock him out.
Back at Anton’s house, he awakes believing he had a terrible dream and runs to tell his friends, finding them still zombies and snacking on his couch. They tell him that his neighbor Randy knows about all things Satan and demons and that he might have some advice for Anton. Anton finds Randy at a fast-food place and asks for help which he replies that he needs to keep his hands busy with other tasks so it won’t kill any more people. The same two police officers from before arrive at his house responding to a noise complaint. They enter his house upon seeing Mick and Pnub’s zombified bodies and accuse Anton of being the killer. After a short confrontation Anton’s hand kills the two cops in his living room. Fed up, Anton flees to his kitchen and cuts off his hand with a cleaver. Pnub and Mick seek out a First-Aid Kit while Anton traps the hand in a microwave, burning it.
Meanwhile, Debi, teaming up with Randy, hunt Anton down to put a stop to the possessed hand. After sending Molly to the school dance, Anton returns home to finish off the hand. Unfortunately, Pnub and Mick inadvertently release the hand. The three then steal Randy's truck and head to the school. Mick and Pnub go to the Halloween dance to watch over Molly, while Anton looks for the hand. Randy and Debi meet up with Anton. Debi explains that the hand will drag Molly's soul into the netherworld. Anton crashes the dance and tries to warn everyone about his hand, but is ignored.
The hand then scalps the band's lead singer and causes a panic. Molly and her friend Tanya escape through the vents. They attempt to go through a fan, which they have stopped with Tanya's shoe, but Tanya gets hung on the rope, Molly tries to pull Tanya off the fan and Anton's hand ends up removing Tanya's shoe, allowing her to be pulled to her death in the fan. Molly then runs into the art room, causing her to get knocked out. Anton enters and fights with the hand while it is inside a puppet but it escapes to the auto shop, where Molly is strapped to a car in her bra and panties, being raised toward the ceiling. Anton, Mick, and Pnub fight with the hand over the controls. Mick finds a mechanic's bong and he and Pnub smoke "for strength". Anton blows some smoke into the hand (still inside a hand-puppet) until it drops the controls and they save Molly. Debi throws a ritual knife into the hand, stopping it in a puff of smoke and fire. She and Randy take off for "ritualistic sex." Anton releases Molly from the top of the car, they go under the car and start making out. In the process of lighting the bong for Mick, Pnub accidentally hits the controls for the car, and Anton is crushed by the car.
In the film's conclusion, Anton is in a body-cast in the hospital, having given up heaven to stay with Molly, and Mick and Pnub are now his Guardian angels. When he is left alone in his room, Anton looks up and sees the message "I am under the bed" written on the ceiling. As Anton screams, Mick and Pnub walk down the hall, pondering if they should tell Anton they were the ones that wrote the message, but decide against it, laughing.