Someone's Knocking at the Door (2009)

In this genre-defying grind-house throwback, a group of drug-addled, sexually deviant medical students are systematically terrorized by Wilma and John Hopper. The Hoppers, serial murderers and rapists, mysteriously return from the 1970s, and bring horrifying psychedelia with them. With comedy, subversion, satire and true gore, the students must face escalating attacks, shocking circumstances and visceral disgust.