She has danced in a cone bra, expressed herself onstage in a white wedding gown and put wearing fishnets, leather or less well into your 50s in "vogue." But Madonna had never gone "Gangnam Style" in one of her wilder-than-thou concerts, until now.

The Material Girl surprised and delighted her New York City audience Tuesday night by bringing onstage none other than Korean pop star Psy, who, she told the crowd, flew in "all the way from Frankfurt, Germany" that morning for the special performance, according to the Associated Press.

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Madonna, performing her second concert in as many days before a crowd of nearly 20,000 at Madison Square Garden, told her fans she was a fan of Psy as the duo performed his signature hit, "Gangnam Style," and her hits "Give It to Me" and "Music," while bumping and grinding onstage.

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Psy, whose real name is Jae-Sang Park, 35, was a little-known South Korean rapper until July when his hilarious, viral music video, "Gangnam Style," quickly catapulted him onto the international stage, gaining more than 118 million views since it was posted to YouTube.

He appeared onstage Tuesday night, in a bright red suit, as Madonna was having fun with a rendition of his famous song.

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Beyond dancing with her famous friend, Madonna, 54, also used Tuesday's concert as another chance to raise money for victims of superstorm Sandy on the East Coast. Fans threw money onstage while she sang "Like a Virgin," adding to the $3,000 she collected at Monday's show, the Associated Press reports.

"This money is not for me," Madonna said during Monday night's concert, where she danced with her 12-year-old son onstage, according to MTV.

"We are collecting money for victims of Hurricane Sandy so please feel free to be generous as I freeze my a** off."