Grammys 2013: Rihanna, Katy Perry, Kelly Rowland: Who Defied CBS's Fashion Memo the Most? (Poll)

FREDERIC J. BROWN/AFP/Getty Images; Jason Merritt/Getty Images

You just can't take the sex appeal out of the Grammys. As was to be expected, a few fearless celebrities ignored – some might even say flouted -- CBS’s strict Standards & Practices fashion memo that memorably banned the exposure of any part of breasts and buttocks and any written obscenities in wardrobes.

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The now-infamous memo also forbade ”bare fleshy under-curves of the buttocks,” “bare sides or under curvature of the breasts,” or exposed “puffy bare skin” around genitals.

At least one rocker attempted to defy the obscenity edict. Deadmau5 ‘s Joel Zimmerman arrived in a hat captioned “Your Shit Bums Me Out.” But his fiance, Kat Von D, got him to cover the offending word with tape.

But nothing stopped Rihanna from wearing a perky, nipple-flaunting sheer red Azzedine Alaia gown. Nor did anything deter Katy Perry from revealing mega-cleavage in a mint Gucci gown with a plunging neckline, encircled with jewels for good measure.

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Jennifer Lopez even bared her right leg all the way to her crotch and posed with it provocatively thrusted, a la Angelina Jolie. ”They didn’t say anything about leg!” she told E!’s Ryan Seacrest on the Red Carpet.

Other offenders included Kelly Rowland, who defied the ban in her sexy, sheer black George Chakra couture gown. "It's so funny! I thought about the dress-code and thought about it again, and that's about it," the singer told reporters backstage. "I respect. See, I wore clothes!"

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Ashanti’s underwear was clearly visible under her sheer dress designed by Tony Ward. And Skylar Grey was one of the first women on the Grammy carpet to defy the memo, flashing -- as MSN noted -- the night's first dose of "side boob."

So we leave it to you to decide. Who was the worst offender – and by that we mean the best – at last night's Grammys?