Despite its subject matter, the film's actual on-screen sexual content is rather tame.
Anna removes her underwear and mounts Ben while he's still asleep. We see her bare butt, and a glimpse of her genitals can be seen from behind as well.
Andrew is seen kissing a woman in tight, close up shots. He then walks in with a bottle of wine, and begins to initiate a threesome with Monica and her girlfriend. He begins to climb on top of her while they're all clothed, and kisses both of them. The women briefly kiss each other. When he sees one of the women holding a strap on, he becomes uncomfortable and stops.
The film is about two men daring each other to film each other having sex for a porn festival. When the time comes to shoot the film, it's actually more awkward than sexual. They kiss, and then remark that it felt terrible, and establish a no-kissing rule. They take off their clothes (chests only), and they awkwardly sit in bed together, just talking, supposedly as a way of preparation. *SPOILERS*
There is some sexual talk, but it's mostly civilized, not lowbrow like most modern comedies.