Scre4m: The Ultimate Shriekquel

Two girls, watching a slasher movie about a psycho in an Edvard Munch “Scream” mask who calls girls at home and them stabs them to death, get a call from a psycho who shows up in a “Scream” mask and stabs them to death. But that was a scene from a movie, Stab 6, which two other girls are watching when their phone rings, a gravelly voice threatens them and — surprise! — one girl kills the other.