Kissing shown. No nudity (all seasons).
When a girl comes over to a boys house, the mom of the boy says to "keep the bedroom door a tad open"
There is lots of making out in this show, specifiaclly more in Season 2.
The word 'hanky-panky' is said once. And there are a few conversations about sex.
In Episode 5 a statue of a woman's breast is shown. Nipples are visible. Two Girls take a photo with it. Topless nude girl statue.
In season 2, charlie and nick talk about 'doing it'
Nick and Charlie have sex twice in Season 3, No nudity.
This show is based around teenage relationships. Most of the theme and scenes are sensitive and sweet but I would say this should be moderate as there are suggested sex scenes with a build up to sex and talk of sex etc.