Psycho Beach Party (2000)

Spoof of 1960s Beach Party/Gidget surfing movies mixed with slasher horror films. Florence Forrest, a not-so-innocent girl in 1960s Malibu, becomes "Chicklet", the first girl surfer at Malibu Beach. Only Florence suffers from dissociative identity disorder and, occasionally, her alter ego "Ann Bowman", a sexually aggressive, foul-speaking girl, comes out, during which time several beach goers are found murdered. The suspects include Chicklet herself, surfer Kanaka, exchange student Lars, and even Chicklet's own mother.