There are numerous end-of-year holidays. Thanksgiving, Christmas, Chanukah, Kwanzaa, and New Year’s Eve are celebrated this time of year, but there’s another holiday that’s celebrated in December. Each December 23, legions of “Seinfeld” fans and many others who are familiar with the popular series pay hommage to “A Festivus for the Rest of Us.” This contrived, alternative holiday was a plot line developed for the beloved Costanza family on the series and was billed as Frank Costanza’s creation. Festivus debuted on December 18, 1997, on the episode, “The Strike.” Instead of a tree, candles or carols, Festivus celebrations involve a metal pole, the airing of grievances and feats of strength. Many believe Festivus was simply a television creation, but the holiday is loosely rooted in fact. Daniel O’Keefe, a former writer for “Seinfeld,” reluctantly admitted that his father, Dan, actually invented Festivus in 1966. O’Keefe told CNN that his little brother let the Festivus traditions slip out, and other writers for the show, including Jerry Seinfeld, felt it would make for a great episode, particularly because the holiday wasn’t beholden to anything political or religious. That was the reason O’Keefe’s father developed it in the first place. The real Festivus had few similarities to the TV version. While there was an airing of grievances, the pole and feats of strength were absent. In addition, Festivus would be celebrated any time between October and May. O’Keefe has written that his father would also nail a bag containing a clock to the wall each year, but he doesn’t know why his father did this. Since 1997, the holiday has become a worldwide celebration, with people gathering around their own metal poles in late December every year.