Muscle Beach Party (1964) on Netflix

Second Beach Party movie has Frankie, Dee Dee, and the beach gang hitting the Malibu beach for another summer of surfing only to find their hangout beach threatened by a small gang of muscle bodybuilders, led by the dim-witted coach Jack Fanny, who move in next door to them. Things get even more complicated with the arrival of a third party, that of a wealthy Italian contessa, named Julie, with her manager S.Z. Matts, and her lawyer, Theodore, who come chasing after Jack Fanny's muscle group for Julie to court the muscle king Flex Martian. But when Julie turns her sights on Frankie, Dee Dee becomes more jealous than anyone else in the picture.