Any fan of the show about nothing knows that Dec. 23rd is the legendary Festivus, the fake holiday celebrated by George's father. It's since become a major meme and some people insist on jokingly abiding by all the traditions outlined in the episode. 

But I didn't know until I read this old article that the "holiday" was actual based on a real event that happened in the life of one of the writers. And as it turns out, he honestly didn't want to put it in the script - until his co-writers found out about it. 

And the rest, as they say, is history. 

“The reality of the holiday was too peculiar to show on television,” [Dan] O’Keefe says. “The real symbol of the holiday was a clock inside a bag nailed to the wall and nearby a sign that says, ‘F*ck Fascism.’ That doesn’t fly on network TV. Either Alec or Jeff came up with the idea of the pole and the strength to weight ratio...”

"The airing of grievances...was an entirely accurate portrayal of the original Festivus. “Airing your grievances was a large portion of the original and it was done into a tape recorder.”

Here's the fascinating story behind the origins of Festivus - the holiday for the rest of us.

‘Stop Crying And Fight Your Father’: ‘Seinfeld’ Writers Tell Us How Festivus Came To Be