I've never been a teenage boy, so the name of the movie escaped me. It was driving me crazy. Then I went to Google. Type “Phoebe Cates” in an image search and it's the first thing that pops up. There are even animated gifs. I have to say, purely from an artistic point of view, she had a nice rack.
The movie is Fast Times at Ridgemont High, famous for starting the careers of an entire generation. And that pool scene.
Directed by Amy Heckerling
© 1982 Universal Pictures