Possibly?

I remember our babysitter watching a movie when I was a kid that I caught a glimpse of, and I think this is it, but I'm not sure. The part I saw had two young kids sneaking up on a teen couple fooling around, I think in a barn. The teens see them and the kids run off laughing, and have some kind of conversation about the facts of life. I thought she said something about it being called Paradise or Island something or other.