Cooper Koch is proud of his masculinity.

The 28-year-old actor appeared on “Watch What Happens Live with Andy Cohen” on Monday and opened up about his role as Erik Menendez in the Netflix hit “Monsters.”

Andy Cohen was counting down Hollywood’s “five most iconic full-frontal moments” when Koch announced, “Just to say, mine wasn’t a prosthetic.”

“Well, that would be my next question!” Cohen, 56, said to Koch, who smiled into the camera as he confessed.

“Congratulations, Cooper,” the “Real Housewives” producer added.

“Thank you,” Koch replied.

Cohen then told the openly gay actor he was “very blessed” – to which Koch replied: “Well hung.”

For a scene in “Monsters,” which tells the story of Erik and Lyle Menendez, who murdered their abusive parents in 1989 and were sentenced to life in prison in 1996, Koch had to reveal everything.

In Episode 3, Koch’s Erik showers naked in prison and turns to another inmate to show him – and the camera – his penis.

In an interview with The Wrap last month, Koch revealed how much he prepared to play Erik on the series.

“I turned my trailer into Erik’s room so I had clothes everywhere, and I had pictures of him on the wall, pictures of me too,” Koch said. “I watched videos of myself when I was very young and I saw how my parents treated me, which gave me a certain level of gratitude towards my family and my parents.”

“I listened to (Erik) and watched him diligently,” he added. “And I had my music, I had all kinds of diaries, all kinds of things that helped me really feel like him and be him.”

The success of Monsters (which also stars Nicholas Alexander Chavez as Lyle) has led to the possibility of the Menendez brothers finally getting out of prison.

Los Angeles County District Attorney George Gascon announced earlier this month that new evidence of sexual abuse against the siblings was being reviewed. A court hearing is scheduled for late November that could result in the brothers being tried again or even released from prison.

Erik, now 53, and Lyle, now 56, argued in their trial that they were sexually abused by their parents, Jose and Kitty Menendez, and killed them in self-defense – but the jury still found them guilty.

“I believe in both,” Koch said in a recent interview with Vanity Fair. “I believe that everything they said on the witness stand is true.”

Koch previously revealed that he spoke to Erik on the phone the night before the Monsters premiere. He later visited Erik in prison along with Kim Kardashian.

“I was able to have a really good conversation with him and tell him that I believe him and have done everything I could as an actor to stand up for him and portray him as authentically as possible and that I think the show really “does a good job representing him,” Koch told Variety last month.

Koch also said that they discussed Erik’s criticism of the show during his and Kardashian’s prison visit.

Monsters: The Lyle and Erik Menendez Story is streaming on Netflix.