http://www.wired.com/wired/archive/10.05/longbets_pr.html
Story on the Long Bets Foundation I linked to earlier. “Cosmologist Stephen Hawking has made a number of high-profile wagers on future discoveries. In 1975, he bet Kip Thorne a subscription to Penthouse (the loser would get it mailed to his home) that a celestial mystery named Cygnus X-1 would turn out to be a black hole. It didn't.”