The Big Snatch

Although IMDb lists this movie with a 1968 date, the movie could not have been made until at least 1971. During the infamous radiator scene, Bart quotes the famous line, "Love means never having to say your horny." This is an obvious play on the famous line from Love Story, which was not released until December 1970. Peggy Church, who was born in 1954 according to her IMDb entry, was certainly older than 14 in this film (although she could have been younger than 18). In addition, the amount of nudity in the film would have been highly unusual for 1968, but it is pretty much in line for a soft-core film released in 1971.