On Friday, October 6, the art world was stunned by a pretty predictable Banksy prank. The street artist’s famous “Girl With Balloon” sold for $1 million pounds to an unknown buyer. This was a “new auction high for a work solely by the artist,” London’s Sotheby claimed. But at the very moment the buzz of the buy began filling the room, a device built into the work’s thick frame started shredding it. All of that…