Festivus is a nondenominational holiday featured in an episode of Seinfeld, a popular American television sitcom of the 1990s. Many people, influenced or inspired by Seinfeld, now celebrate, in varying degrees of seriousness, the holiday in real life. Festivus is celebrated each year on December 23. Source: Wikipedia. Festivus Holidays Society.
Festivus is both a parody and a secular holiday celebrated on December 23 that serves as an alternative to participating in the pressures and commercialism of the Christmas season. (wikipedia)