Lady Gaga crowd surfs at Lollapalooza

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Lady Gaga and a friend take in a New York Subway Series game between the Mets and Yankees. (Al Bello/Getty Images)

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MLB may have an issue with Lady Gaga’s uniform. (Al Bello/Getty Images)

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Lady Gaga raises the roof while taking in a Mets-Yankees game. (Al Bello/Getty Images)

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Lady Gaga celebrates in a skybox at Yankee Stadium. (Al Bello/Getty Images)

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Lady Gaga attempts to quench her thirst. (Al Bello/Getty Images)

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Lady Gaga knocks back a cold one at Yankee Stadium during a Mets-Yankees Subway Series game. (Al Bello/Getty Images)

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Lady Gaga at a Mets-Yankees game at Yankee Stadium. (Al Bello/Getty Images)

[Warning Graphic Content]

Internet - Fair Use

March 10, 2014 6:12 AM PT

Lady Gaga, already in Chicago to perform at Lollapalooza, jumped on stage during a set by Semi-Precious weapons. And here's what happened.

WARNING: Lady Gaga's outfit is a bit adult.