Watch: Cooper Koch Says His 'Monsters' Nude Scene Was All Natural: 'That Was Not A Prosthetic!'

How's this for naturalistic acting? Cooper Koch, who plays Erik Menéndez on Netflix's "Monsters: The Lyle and Erik Menendez Story," fessed up to Andy Cohen that what you see in his full-frontal moment is 100% real.

Koch "confirmed that he went au naturel during his Monday, October 14 appearance on Bravo's 'Watch What Happens Live,'" Us Magazine reported.

The two were discussing full-frontal scenes and ranking some from movies past, E! News said, when Koch made sure to point out the "Monsters" scene's bona fides, telling Cohen, "Also, just to say, mine was not a prosthetic." He pointed a finger and grinned mischievously to underscore the message.

He evidently read his host's mind: "Well, that was gonna be my next question!" Cohen sputtered.

"Sorry," the 28-year-old actor, who clearly has little to apologize for, responded.

Cohen, not noticing the apology, continued: "Congratulations to you, Cooper! You're very blessed, aren't you?"

After mouthing a "Thank you" to Cohen, Koch said, "Well... hung," the devilish grin still in place.

"The controversial scripted show, created by Ryan Murphy, centers the Menéndez brothers' high-profile trial for killing their parents in 1989 and explores their claims that they were sexually, physically and emotionally abused by José and Kitty Menéndez," Us relayed.

As previously reported, the real Erik Menéndez went after the series, posting a denunciation of the Netflix show on X (formerly Twitter) via the account of his wife, Tammi.

Menéndez slammed the show for what he called a "caricature" of his brother, Lyle Menéndez (played in the series by Nicholas Alexander Chavez), and declared that there were "horrible and blatant lies rampant in the show..."

Menéndez also accused the show of "tak[ing] the painful truths several steps backward – back through time to an era where the prosecution built a narrative on a belief system that males were not sexually abused, and that males experienced rape trauma differently than women."

A key point of the brothers' defense was the claim that they believed their parents were planning to murder them, and they were acting in self-defense.

"It makes sense that he would feel that way," Us Magazine recalled the out gay actor telling Vanity Fair. "This is the worst part of his life being televised for millions of people to see, and not to mention in this dramatized, fictionalized, Hollywood TV way. I get how he feels, and I stand by him."

Koch, who has several impressive scenes in the series – including an unbroken shot in which he narrates, in graphic detail, the abuse his character supposedly suffered – told Vanity Fair that he believes the claims made by the brothers at their 1994 trial were true.

"I believe everything that they said on the stand to be true," the actor declared.

Watch Cooper Koch's exchange with Andy Cohen, embedded in the tweet below.