We see brief full frontal (although his hand covers most of his private parts) and rear nudity of a dead man.
Discussion of sex takes place a number of times throughout the film, some of it is moderately graphic.
Several times we see full nudity of a dead woman, this includes close up shots of her breasts and partial views of her pelvic area. Some of these shots last for a good while.
A prostitute and john starting making out, a little bit later we see her in just her underwear, and he is is behind her groping her bare breasts. He does as he bends her over, but she refuses. Instead she pulls down his pants and starts performing oral sex on him. We see he full rear nudity as well as several full views of the sexual activity (no view of his genitals) we then see his facial expression as he comes. We then see the prostitutes hand over her mouth and she leaves to presumably spit it out (we see her bare breasts again briefly).