Dave Letterman joked in his monologue of Dec. 23, 2010. The CBS censors cut that bit from their Late Show webpage so don't bother checking.
Christmas is ostensibly a religious holiday (but it really is nothing of the kind) and the modern celebrations associated with it, have been criticized for being too commercial, too material and too gleeful, for a religion that worships self-sacrifice and rebirth into the after-life. Since Christianity (and several other religions) have a large antilife component, the celebration of the birth of a saviour deserves a more serious tone according to Christian orthodoxy.
In a wonderful essay, first delivered on a radio show fifteen years ago, Leonard Peikoff explains how the Christmas celebrated today by Canadians and Americans was an invention of post-Civil War America, a creation of "the happiest nation in history."
Dr. Peikoff was born a Canadian (Winnipeg, Manitoba) in 1933, and became heir and executor of the estate of Ayn Rand upon her death. I first read his work in The Objectivist magazine 40 years ago. Today he is a leading advocate of Objectivism and founder of the Ayn Rand Institute. His essay is published annually in Capitalism Magazine and can be viewed here. Enjoy, and Happy Christmas!