From the NYT via No More Mr. Nice Blog:
The first surprise is that from Tampa Bay, Fla., to Washington, from
Austin, Tex., to Oxford, Ohio, many real people are holding parties celebrating Festivus, a holiday most believe was invented on an episode of "Seinfeld" first broadcast the week before Christmas in 1997.
The actual inventor of Festivus is Dan O'Keefe, 76, whose son Daniel, a writer on "Seinfeld," appropriated a family tradition for the episode. The elder Mr. O'Keefe was stunned to hear that the holiday, which he minted in 1966, is catching on. "Have we accidentally invented a cult?" he wondered.
"It was entirely more peculiar than on the show," the younger Mr. O'Keefe said from the set of the sitcom "Listen Up," where he is now a writer. There was never a pole, but there were airings of grievances into a tape recorder and wrestling matches between Daniel and his two brothers, among other rites.
"There was a clock in a bag," said Mr. O'Keefe, 36, adding that he does not know what it symbolized.