Steve Wynn is a Las Vegas casino mogul, and the owner of a substantial art collection. In October 2006 it was announced that he had damaged Le Rêve, a Picasso painting he had agreed to sell for $139million (this would have been a record price for a piece of art). It emerged that he had punctured the picture with his elbow while showing it to friends. There's an great article about the incident here in the New Yorker, and Nora Ephron, who was one of the friends who in the room at the time, wrote a blog piece about it here. It seems he took the incident in great spirit.