The Slumber Party Massacre is a 1982 American slasher film directed by Amy Holden Jones and written by Rita Mae Brown. In the film, an 18-year-old is left alone by her parents and plans on celebrating a slumber party with her invited friends, not knowing that a murderer using a power drill has been unexpectedly invited and begins a killing spree.
The film was originally written as a parody of the slasher genre, however, when it was submitted to the filmmakers, they filmed it not as a parody, but a straight genre film. As a result, the movie displays a lot more humor, both intended and unintended, than others of this genre. When originally released, the film received negative reviews, but later developed a cult following in the years.
(Summary from Wikipedia)