Robert Pattinson wants everyone to know why he thinks the "Twilight: Breaking Dawn" sex scene was really  edited -- there was "a bit too much butt crack."

Pattinson and the rest of the cast stopped by the Ellen DeGeneres Show -- where Rob tried to dispel the rumor that the scene was re-shot due to Kristen Stewart's over-zealous, uh, participation.

"There was a bit too much butt crack I think," he tells Ellen. "That was one thing I know they cut out. They didn’t cut the shot or what ever they just cut the crack out."

So how exactly do those magic movie editors remove a butt crack?

"They just painted over it ... you’re allowed to show cheek," Rob explains. "You can’t show crack."

The full interview is set to air on Nov. 18.