She’s played just about every role possible, but even Keira Knightley admits she “completely lost it” while filming her latest steamy scene for the upcoming movie, “The Duchess.”

The British actress couldn’t keep it together when her costar, Dominic Cooper, was forced wear a skin colored diaper for a sex scene.

She says, “Sex scenes are never the easiest and you’re meant to be very supportive of each other, but I just completely lost it.”

Apparently Ms Knightley, who recently turned 24, about fell over laughing during the filming. The director had to tell her, “Pull yourself together.”

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