Kevin Mazur/WireImageMadonna's concert in New York City on Monday night turned into a very unlikely fundraiser for the victims of Hurricane Sandy: The star announced she was stripping for donations.

Telling the crowd that she and her children had just visited New York's Rockaway Beach, one of the areas that was the hardest hit by the late October superstorm, Madonna added, "It was really sad but we also saw amazing acts of humanity."

Then, later in the concert, Madonna invited people to throw money on stage while she removed her clothing, which she does each night as part of a sequence during which she performs a slowed-down version of "Like a Virgin."  Announcing that she was showing her "naked [butt] for Hurricane Sandy victims," she added, "Please feel free to be generous as I freeze my [butt] off."  Bills rained down on the stage, but it's unclear how much money was actually collected. 

In other Madonna news, her latest album, MDNA, has been certified gold for sales of half a million copies, according to The Hollywood Reporter.  It took the album seven months to reach that mark, which is partly due to a general slowdown in music sales, and also possibly due to the fact that the album only featured one top 10 hit, "Give Me All Your Luvin'."  Still, it's the 20th gold album of her career.  Among female artists, only Barbra Streisand has had more.

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