The Last Man (2000)

There is no frontal nudity. A man's bare butt is seen briefly. There is no sex shown but it is implied. The implication of sex however is so subtle that I am not sure there is any sex more than once. A man and a woman is seen sleeping together a few times but no sex and no nudity. There is much talk by a man about getting sex.

Near the beginning, a woman takes off her top, presumably for sex, and she is seen topless briefly but only from the back. The scene ends there. She is later seen again topless but again only from the back. She is later seen far in the background naked but only from the side and she is covering her breast with her arm.

All of the sex is just talk and not explicit.