White Fire (1976)

One of the girls has long dark hair and a tight, slim body — she’s outside in the snow, hands on her head, totally naked, shivering a little. The other brunette is shorter, similar build, and they both end up inside with a dude in a bathroom, all three of them nude. The guy’s built, muscular, and he’s jerking off while watching them. They take turns on their knees, sucking him, then it shifts to one girl bent over, getting fucked in doggy style while the other plays with her tits. Camera stays medium-shot, natural light, feels unscripted. The whole thing’s low-key but nasty, especially the contrast between the cold outdoor shots and the hot indoor group stuff.