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Gotta keep it PG-13!

Robert Pattinson and Kristen Stewart's steamy sex scene in Breaking Dawn will be missing one key thing: Edward Cullen's "butt crack!"

In an appearance on The Ellen DeGeneres Show that airs Friday, Pattinson, 25, explained why his anatomy had to be blurred out. "There was a bit too much butt crack, I think," he quipped of his and Stewart's love scene. "That was one thing I know they cut out. They didn't cut the shot or whatever, they just cut the crack out."

DeGeneres, 53, asked how it was possible to "cut the crack out," to which the actor replied: "They just painted over it!" 

"They cover it so there is no crack on your butt?" DeGeneres asked. "You just look like one solid cheek?"

Pattinson had a simple explanation: "You're allowed to show cheek. You can't show crack."

Stewart, 21, told MTV News the sex scene with her real-life beau was "all close-ups" and "not a beginning-to-end sex scene; it's memories."

Pattinson, meanwhile, joked that he felt "kind of like the coolest person" during the pivotal Breaking Dawn moment. "[I thought], 'This is easy! I can fulfill people's sexual fantasy expectations without even thinking about it, piece of cake.' That isn't acting."

The Twilight Saga: Breaking Dawn - Part 1 opens in theaters this Friday.