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 / Updated  / Source: Access Hollywood

What happens in Vegas, may stay in Vegas. However, there’s one Sin City memory Kate Bosworth can’t talk about even if she wanted to.

Bosworth revealed she was so drunk while filming a steamy love scene with Jim Sturgess in “21,” she can’t even remember it.

"We were both so drunk," the sexy “21” siren told People. "Jim and I became such good friends, we decided to have a couple of drinks, loosen up and go for it."

In “21,” Sturgess plays Ben Campbell — a shy but brilliant MIT student — needing to pay school tuition – who joins a group of fellow brainiacs that attempt to turn the odds in their favor in Las Vegas.

Bosworth plays the sexy Jill Taylor, a fellow student who helps seduce and recruit Ben to join the group of card-counting gamblers.

The film is based on Ben Mezrich’s book, “Bringing Down the House: The Inside Story of Six MIT Students Who Took Vegas for Millions.”

So what was the stars’ drink of choice on the set to prepare for their love scene?

"We were on Grey Goose, I think," Bosworth told People on Wednesday at the Cinema Society and Calvin Klein Jeans-sponsored screening of the film in Manhattan. "It was brilliant for about half an hour. As we continued to drink … it just became sloppy and messy. I couldn't stand up at one point."

“21,” which also stars Kevin Spacey and Laurence Fishburne, opens nationwide on March 28.