She Came on the Bus (1969)

A gang of horny, sadistic juvenile delinquents looking for kicks invades the suburban home of a housewife, injects her with dope and waylays her. A passing saleswoman receives similar treatment. The gang steals the housewife's car and heads for the open road. They hijack a bus, kill the driver when he objects, and assault two female passengers, one of whom enjoys it. She convinces her friend to play along, and they all get their kicks