Lady Gaga Would Totally Go to That AC/DC Concert With Your Dad

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AC/DC reunited with their former drummer Chris Slade to open the Grammys tonight with "Rock or Bust" and "Highway to Hell." And while some people looked a little confused (we're looking at you, Katy Perry!), Lady Gaga was super-pumped from the jump, doing what seems like a mix between a fist-pump and air guitar.