Are you referring to the 1980, film starring Christopher Atkins and Brooke Shields?
This is a cult-classic (now) and is one of those films that anybody of any age should see because it deals with a very intriguging subject: If there was no one to teach you about adolesence, how would you cope?
The sequels were awful, but this is the film that launched Brooke Shields' career and made her a household name and for that reason alone, one should see the film just to see where she got her major break apart from modeling