There is male buttock nudity in one episode (locker room of the football team). Sex is not directly shown, but discussed between characters.
In one episode, we see two characters kissing, the girl points down and you see the man go down out of frame before the scene ends. Oral is implied but nothing is shown.
There also are mild sexual references.
A man is repeatedly referred to as a "wanker".
Several pictures of scantily dressed women (one of which is topless) are visible in a man's locker. Lasso puts tape over the sensitive area.
At one point, several sketches of a woman's breasts are shown
In season 2, a woman masturbates. Her lower half is covered by bedsheets but it's very obvious what is happening.