UK street artist Banksy caused a stir (轰动) earlier this month. It was at an auction (拍卖会) in London on Oct 5. It was announced that his painting Girl with Balloon had been sold for $1.4 million (9.7 million yuan). But as the auctioneer spoke, half of the painting started moving down and coming out of the frame (画框) in pieces. In a video Banksy released the next day he said he had secretly fitted a shredder (碎纸机) into the frame some years before.