Planet of the Apes
One of my all time faves and certainly the one with my favorite nude scene. Got a note on Facebook that this movie opened 50 years ago today.
My favorite scene is the skinny dipping scene about 20 minutes in. After crashing on a planet and knowing they are 2000 years into the future, 3 astronauts look for signs of life, just to keep themselves alive. When they stumble on plant life, then a large body of water they strip down completely and enjoy swimming. As they ditch the duds, they have such great joy and my 12-year-old self wanted to -- HAD to -- do that at some point.
The coolest part, to me, is the fact that their clothes get stolen and destroyed, leaving them permanently nude!!!
Okay, okay, they find the remnants and fashion some little loincloth/shorts things and the humans they encounter are inexplicably clothed when you know they should not be. But any other movie you can name, the nude characters have some clothes they can access SOMEWHERE.
In the original book, the main characters get stripped by the naked humans and remain that way for most of the rest of the book, which is a bit more "realistic" (loosely used). And in the Marvel comics version, the humans are nude until they are captured, although one of the reprints has them wearing shorts when they go swimming.
Well, this was the first time I saw naked people in a movie, and just got into the joy the characters felt when they came upon the water and freed themselves. Had a great influence on me and my attitudes (and desires) around nudity.