There is a quick scene where a naked woman is sitting on a man's lap. In a quick second you see her nipple and her bare backside when she stands up to leave.
Most episodes have no sexual content at all, and when it does, it isn't graphic.
The sex/nudity is never graphic. Many adult topics are talked about throughout the show. Some scenes show breasts, and buttocks but it's always quick and non-explicit. There are a few sexual scenes, but not too graphic.
There are a few sexual situations, including (strippers/prostitutes(no nudity), as well as a few scenes with brief nudity(side breast etc), and only a small amount of sex scenes through the entire show which is 89 episodes.
In Season 3, Vic forces a prostitute to take a gun in her mouth saying "Take it." Very jarring and unsettling with its overtones.
There are several graphic sexual references.
Some themes deal with prostitution, child pornography and rape. Rape is discussed when investigating crimes and is shown a couple of times. Male and female buttocks are shown rarely. Instances of this include a streaking prank in the police station, a strip search of a male suspect with minimal nudity shown, and a few sex scenes.