The main character repeatedly experiences pain-induced orgasm, but this is depicted only in a highly stylized way, by darkening of the eyes and by waves of optical distortion radiating from his head. His primary-school-age son also exhibits these symptoms once, when a pretty woman speaks to him.
Sex is implied to happen once near the end of the film, but this only becomes clear after the fact.
The Bondage women dress in mildly skimpy attire, and the CEO's outfit emphasizes her cleavage. The main character and his son are seen in their underwear, and once they are shown trussed up in minimal clothing. They are shown taking a bath; the child is fleetingly seen from the front as he exits the tub.
Despite the premise of the movie - paying to be attacked by experts in bondage, domination, and sadism -- there is neither sexual nudity nor any on-screen sex scene, nor any particularly strong sexual dialog. There are some disturbing (albeit comical) fetishism scenes though.