Can you tell me the name of/recognise this movie?

The movie was from sometime in the 70's or 80's. It was a comedy set in the late 50's or 60's about a boy named Johnathon trying to lose his virginity during high school. A lether jacket wearing boy, new to town and bored out of his mind, helps his new friend start dating one of the prettiest girls in school, thereby getting the attention of one of the girls girlfriends in the process. The movie was sort of a early tamer version of American Pie. When Johnathon finally gets his chance to be with the popular pretty girl he forgets to bring protection, but they do it anyway but she doesn't want him to go all the way, but her attention is on her dog that is watching them and doesn't realize he went all the way, then her parents come home and he ends up hanging from her window naked in broad daylight. Anyway, anybody remember the name of this movie? There were a few quips about Montgomery Cliff and in the end the biker friend runs off with his girlfriend.