Doll Face (1987)

An angelic 'Doll Face,' Sandy Summers, listens as her mother and stepfather, Ken, make love all night. Four years later, she arrives at Ken's San Francisco doorstep, invading his new life with Rita, since she can no longer get along with her real mom. Trying to get her mind off her ex-stepfather's love plunger, she takes in a sleazy San Francisco North Beach sex show and on a second trip becomes a willing part of the 'audience participation.'