(CNN) -- It's December 23, so "let's rumble!"
As last-minute shoppers fueled on eggnog scramble for those final gifts for relatives thrice-removed, there's another celebration afoot Tuesday: Festivus.
Festivus was introduced in the ninth and final season of "Seinfeld" as a holiday that George Costanza, played by Jason Alexander, begrudgingly grew up with as an antidote to the season's growing focus on consumerism.
While the episode originally aired on December 18, 1997, the holiday and its eccentric customs -- like the "feats of strength" and "airing of grievances" -- live on with much fanfare.
"Many Christmases ago, I went to buy a doll for my son. I reach for the last one they had -- but so did another man. As I rained blows upon him, I realized there had to be another way!" George's father, Frank Costanza, played by Jerry Stiller, explained in the episode.
And so a "Festivus for the rest of us" was born.
The Twitterverse is rife with Festivus references this time of year.
"HAPPY FESTIVUS!" Alexander exclaimed Tuesday on the site. "May ur pole be straight, ur feats be strong & your grievances be few. With love from the Costanzas - Frank, Estelle, George."
HAPPY FESTIVUS! May ur pole be straight, ur feats be strong & your grievances be few. With love from the Costanzas - Frank, Estelle, George— jason alexander (@IJasonAlexander) December 23, 2014
Festivus has even spawned literature like a 2005 guide to the holiday called "Festivus: The Holiday for the Rest of Us."
Despite the absurdity of it all, Seinfeld writer Dan O'Keefe said he, in fact, grew up with this peculiar holiday of his own father's creation, and the "airing of grievances" into a tape recorder was a real part of it.
However, the pole and the father-son wrestling match were made for TV.
"I was not forced to wrestle my father. If I had, I would've been raised by the state of New York," O'Keefe told CNN in a 2013 interview about the "feats of strength" that appear in the episode.
Much like Costanza, O'Keefe didn't want the tradition to leave the family circle.
"I didn't want to put it on TV because it was sort of a family disgrace," O'Keefe joked.
But when the show's other writers and Jerry Seinfeld caught wind of it from O'Keefe's brother, majority opinion prevailed.
Fellow writer Jeff Schaffer came up with the Festivus aluminum pole, which fans can now purchase online.
The real symbol was a clock in a bag nailed to the wall, which O'Keefe says his father still hasn't explained to him.
"I thought it was going to be the most forgettable part of it that was cut out for syndication," O'Keefe said.
Instead, the pole and the holiday took on a life of their own. And that is a Festivus miracle.