Graphic nudity is shown on a few separate occasions.
In an early scene, the protaganist goes to a doctor to ask questions about erectile dysfunction. Some brief nudity is shown as he is examined.
In another scene he visits a sex surrogate/sex therapist, to help him become more at ease with his body and sexuality. He lies completely nude on a massage table while the female therapist runs her hair and hands across his naked body. His bare buttocks are visible. Then he turns over and his full genitalia can be seen. She proceeeds to massage him and even grabs his penis and testicles and holds them in her hand. The camera angle changes and we see a graphic shot of his genitalia as his crotch is in full view.
The final scene involving nudity shows the main character stripped completely naked and chained to a cross. His penis is fully visible for an extended period of time as a dominatrix whips him and slaps and grabs his genitalia.
So there are three scenes involving full male genital nudity and genital touching, as well as strong themes of sexuality, humiliation, and degradation. This is mostly played for comedic effect, rather than eroticism. The film would likely receive an NC-17 rating by the MPAA.
Much of the focus is on sex and erectile dysfunction. Many verbal references throughout relating to sex.