What happens here, stays here, runs the official slogan of Las Vegas. Steve Wynn, the man who built much of Sin City's wealth, must be wishing that it were true.The billionaire, a real estate mogul and casino king and art collector, inadvertently put his elbow through one of the paintings in his office, leaving a small hole in the middle of the canvas. Unfortunately the painting at the receiving end of the errant limb was a 1932 Picasso that Mr Wynn had just agreed to sell for $139 million,making it the most expensive piece of art ever sold. Late last month Mr Wynn invited guests to see the painting, which hangs in his Las Vegas office, before it was sent to the buyer, a hedge-fund mogul, Steven Cohen. Mr Wynn began to explain the painting's provenance to his guests, gesturing enthusiastically about the finer points of the picture's erotic subtext. "So then I made a gesture with my right hand," Mr Wynn told the New Yorker magazine, "and my right elbow hit the picture. It punctured the picture."According to the screenwriter Nora Ephron, a member of the party, Mr Wynn's reaction was slightly more colorful. "Oh shit, look what I've done," Ephron recalls him saying.