Tir à vue (1984)

In one scene, a guy opens a curtain and sees a 17-year-old girl holding her shirt open to expose both breasts.

Right after that comes a hot sexual intercourse segment. For about 12 seconds we watch a guy standing and the girl against a ladder with her legs wrapped around him and he repeatedly pounds into her. Each thrust causes them to move up and down, and her breasts bounce a bit from that. After a change of shot we see him behind her and holding her breasts while they both face the camera. Once again they move up and down and continue getting it on, albeit in a different position than before.