Letterman: Matt Stone & Trey Parker Talk 'Sheening Out' At 2000 Oscars (VIDEO)

"South Park" gurus Matt Stone and Trey Parker stopped by "The Late Show" Monday night to tell David Letterman all about their new Broadway musical "The Book Of Mormon," but also ended up explaining something they did 11 years ago.

As Letterman's post-Oscars night guests, Letterman thought it only appropriate to question the boys on their notorious trip to the Academy Awards in 2000 where they wore dresses a la Jennifer Lopez and Gwyneth Paltrow. When Letterman asked how they went through with it, Parker said that after many people doubted them they just started "Charlie Sheen-ing" and were ready to go.

"We were just 'Sheening' our heads off," Parker explained.

Letterman finally whipped out the infamous photo of the boys wearing J. Lo's low-cut, blazing green Grammys dress and Paltrow's pink "Shakespeare In Love" gown.

"You can tell that we're both 'Sheening' pretty hard right there," Stone reiterated.

We can only imagine what that means.