Festivus is from the Seinfeld episode “The Strike.”

Festivus is a fictional holiday featured in the Seinfeld episode titled “The Strike.” The episode first aired on December 18, 1997, during the show’s ninth season. The concept of Festivus was introduced by the character Frank Costanza, played by Jerry Stiller, as an alternative holiday to Christmas. The holiday includes unique traditions such as the “Airing of Grievances” and “Feats of Strength.” The holiday is celebrated on December 23rd and instead of a Christmas tree, an unadorned aluminum pole is used. The concept of Festivus was actually based on a real-life family tradition of one of the Seinfeld writers, Dan O’Keefe.