Madonna Flashes Butt in Concert

She's not sorry, indeed!

In Rome on Tuesday, during the latest stop on her MDNA tour, Madonna gave concertgoers a glimpse of something special -- nearly mooning the audience in barely-there skivvies.

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Days after exposing her nipple to fans in Istanbul -- outraging some -- during her song "Human Nature," the 53-year-old pop legend and mother of four pulled a similar stunt during the same number in Italy.

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Clad in a sexy lace bra and trousers, with her blond locks swept up in a dramatic retro 'do, the Grammy winner yanked down her black pants, revealing her posterior in a lacy, G-string bottom. (Appropriately enough, the 1995 song "Human Nature" is all about Madonna's unapologetic stance for her explicit, edgy "Erotica" album and "Sex" book of the early '90s.)

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The icon was criticized in some corners for showing her breast in Istanbul last week during the striptease routine. "What works for a 22-year-old woman or a man is not appropriate, very often, for a 53-year-old," Donny Deutsch complained on "Today" recently. Dr. Nancy Snyderman also complained. "Not special," she said. "Not a special breast, not worth doing."

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