05/12/2010 09:26 am ET | Updated May 25, 2011

Will Forte On Nudity, Male Make Outs And Working For Letterman (VIDEO)

'MacGruber' and 'SNL' star Will Forte was on Letterman Tuesday night to talk about his new film, and discussed its graphic nude scenes, internet reaction to his make out with James Franco and his days working as a writer Letterman's show 13 years ago.

'MacGruber,' rated R, features gratuitous nudity on Forte's part, including a scene featuring no clothes and a celery stalk.

"I'm on this set, and I'm completely naked, and I'm cupping my genitalia, and I'm about to place a piece of celery in a place God did not intend celery to go," Forte said. "I looked up, and my mom had to come to the set, and she had come with her two friends."

He then mimicked her look of horror.

After that and some talk about his "very wet" kiss with Franco on SNL, there is a clip of Forte in a Letterman skit from his days as writer on the show, circa 1998. WATCH: