Knightley Loves Nappys!

Pirates of the Caribbean actress Keira Knightley reveals that filming for her new movie, The Duchess, was a blast.

However, she admits that it was difficult for her to maintain a straight face while filming sex scenes for it. "Sex scenes are never the easiest scenes to film and you are meant to be very supportive of each other," she says. Knightley admits though that seeing her costar and on-screen love interest, Dominic Cooper, in nothing but flesh-colored, concealing underwear was not exactly sexy, but hilarious. Although the underwear was worn to make Cooper appear naked on camera, it only succeeded in making Knightley burst out in laughter. "I couldn't stop laughing. He's a very good-looking guy but he's standing there naked apart from a skin-colored nappy," Knightley reveals, according to AceShowBiz.

"It's the most unsexy thing ever. The director even had to ask if I could be a little more supportive and I had to say 'no - he's wearing a nappy!'" Knightley explains.

In order to see whether or not Knightley will be able to keep a straight face, make sure to check out The Duchess in theaters on September 19.