By Rich McKay (Reuters) – Shecky Greene, a comic legend of the old-school Las Vegas lounge acts who rubbed elbows with yesteryear entertainment greats, died on Sunday, his widow told the media. His wife of 41 years, Marie Musso Greene, told the Las Vegas Review-Journal that her husband, born Fred Sheldon Greenfield in Chicago, died of natural causes at their home in Las Vegas, Nevada. Greene, who served in the U.S. Navy in World War II, headlined Vegas acts in the 1950s and 1960s where he was famous for foregoing his planned comedic routines and improvising jokes while walking through the audi…