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Katy Perry knows how to pull a prank.

In a chat with, the "I Kissed a Girl" singer reveals that she and an ex staged a wedding when she was 21.

"We went to Vegas on a whim and we decided to get fake married," says Perry, now 24. "We took all the pictures with the minister, with the fake cake, in the fake chapel and got a fake marriage certificate. We went and bought a wedding dress and a suit at a thrift store, and scanned the pictures and the certificate to my family members, my manager at the time [and] totally freaked the s--- out of them."

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Adds Perry (who split with Gym Class Heroes' Travis McCoy last year), "It was the most hilarious, stupid prank I've ever pulled."

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To this day, she says she still has "the wedding dress and the certificate."

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The experience even inspired her latest single.

"'Waking Up in Vegas' is basically a song about getting into trouble with your best friend or your boyfriend or your girlfriend -- or whoever you're with -- and not having any 'I'm sorry for what I did,'" she says.