http://en.wikipedia.org/wiki/Festivus
Festivus is a nondenominational holiday featured in an episode of Seinfeld, a popular American television sitcom of the 1990s. It was featured on episode number 166 of the show, entitled "The Strike", which first aired on December 18, 1997. Many people, influenced or inspired by Seinfeld, now celebrate the holiday, in varying degrees of seriousness.
According to Seinfeld, Festivus is celebrated each year on December 23, but many people celebrate it other times, often in early December. Its slogan is "A Festivus for the rest of us!". An aluminum pole is generally used in lieu of a Christmas tree or other holiday decoration. Those attending participate in the "Airing of Grievances" which is an opportunity for all to vent their hostilities toward each other, and after a Festivus dinner, The Feats of Strength are performed. Traditionally, Festivus is not over until the head of the household is wrestled to the floor and "pinned".