Unwilling Lovers (1977)

Starts with a blonde MILF and a brunette sitting around a piano, chatting like it’s just another day. Then it cuts to a dark room where a short, messy-haired girl’s on her knees giving a sloppy blowjob to a standing guy. Things ramp up fast—four people in a bedroom, all over each other in missionary and doggy. One girl’s got long straight blonde hair, another’s a curvy brunette with waves. The lighting’s dim and green-tinted, but you catch every detail: the way they’re all tangled up, the way the girls ride cock like they mean it. Later, there’s a shot of just a pair of tits in close-up, then the group moves to what looks like a theater entrance, still buzzing from what just happened.