First movie scene you remember being turned on by

Barbarella (1968)

https://www.youtube.com/watch?v=rnS5LYvaYhc

Can't recall if it was the first scene ever but it was the first to really have an impact on me. An Aussie film called "Man of Flowers" it has a young woman undressing (full frontal nudity) for a man. Nothing happens, she just undresses for him but I was only 10 or so at the time so it was really erotic for me.

Kate Winslet in Titanic. I was 8 at the time. My parents wouldn't let me watch that one scene, but I watched it later when they weren't around. Let's just say that, as time went by, that part of the tape... got a little worn.

Clan of the Cave Bear

Beyond the Valley of the Dolls (1970)

Sex scene in the first "Friday The 13."

Jean Simmons' in the pond scene in Spartacus.
You can see it at 3:12 of this vid ... https://youtu.be/88g0Gq0ytlw

The sex scene in Terminator.

Also when Vanity pulls down her dress in Action Jackson.

Ahh, the mammaries!