The classic tradition of standing around crying while Leap Day William tosses candy. (Photo: NBC)

It’s hard to believe that it’s been four years since we met Leap Day William.

For the uninitiated—someone who is not a 30 Rock superfan—Leap Day William is the keystone of a leap year tradition, where you wear blue and yellow; you stand around and pretend to cry so Leap Day William showers you with sweets (“He emerges every four years to trade children’s tears for candy”); if you see someone not wearing yellow and blue, you are entitled to shout, “Poke your eyes, pull your hair, you forgot what clothes to wear,” and poke and pull.

Leap Day William himself has a complicated backstory. Part Santa Claus, part sea monster, he appears as an old man twirling a Mark Twain-style mustache and wearing (of course) a blue suit with a wide-brimmed hat. He spends every day besides Leap Day underwater (“the Mariana Trench”), and, in the depiction starring Jim Carrey as Dave “Leap Day” Williams and Andie MacDowell as his wife on 30 Rock, appears to have grown gills.

Mostly, though, Leap Day William and Leap Day in general exist to remind you to take chances. It’s an excuse to follow your dreams. Or, as the characters on 30 Rock keep telling each other, nothing that happens on Leap Day really counts.

But where did this creation come from?

“Leap Day William threatened us,” says 30 Rock co-creator Robert Carlock. “He made us do it.”

Like many things on the internet, Leap Day William has taken on a life of its own—type in ”Leap Day William” and see autofills like “Is Leap Day William real”—but the holiday and the character are wholly unique to the show. The idea came up during shooting.

“We had been talking about leap day and this whole mythology arrived, which we loved instantly. Like Woollie, a whole other world opens up to you. You have all the short hand, the millennia of traditions, with so many holidays,” he says. “It was as if we had a completely untouched new Christmas.”

Jim Carrey, playing Dave “Leap Day” Williams on 30 Rock. (Courtesy of NBC)

And indeed, in the episode (season six, episode nine, “Leap Day”), the holiday is obvious to all the characters, each of whom, in their own way, have to figure out how to spend this extra day. (One problem that Carlock remembers is how to explain why the show had ignored the previous leap day, which became a line about Tina Fey’s character, Liz Lemon, being on a cruise.)

Liz has to decide whether to accept her college-friend-turned-internet-billionaire’s indecent proposal (take Thad’s virginity for $20 million), Jack has to perfect his work-life balance, Tracy has to spend his Benihana’s gift card before the clock strikes March 1. And, then, of course, there’s the movie-within-the-TV show, running in the background.

What would be a fake holiday on the internet without fan art? (Photo: Tumblr)

“I don’t know how we got them,” says Carlock, referring to Carrey and McDowell, “But they both said yes right away.” In particular, Carrey was excited. “We met with Jim who was bubbling over with ideas. Tina had to say, ‘We’re shooting this tomorrow, Jim, I don’t think we can go to the Empire State building.’”

But Carrey did get to add a few things, as they filmed the bare bones of a conventional Santa Claus tale. When Carrey is running down the street at the end, shouting a series of non-sequiturs (“I saved Leap Day and connected with my son and I solved a big case from earlier!”), he is ripping off his clothes. “That was not scripted,” Carlock says, “on a pretty cold day.”

The choice to make the Benihana part, where Tracy has to work off a ridiculous gift card to the restaurant in one day, had real-life inspiration. “Tracy Morgan himself is a great fan of Benihana. We shot at Benihana and everyone who worked there knew him,” Carlock says. “This came from our sense that, at least, he gets to eat something he likes while shooting.”

But why the gills on Leap Day William? “When the world changed, some of the old gods, the Vikings and the Romans and the Assyrians, some of them hid,” Carlock says, “a bubbly god of chaos has taken on the form of Leap Day William. I don’t know if he had gills before he hid from the new order, or if he’s real.”

Like the Easter Bunny or Santa Claus, Leap Day William is a mythological mess, and if the show’s last shot is any clue, maybe don’t follow him down a dark alley. But he delivers a lesson we can all heed today: carpe diem. Or as another character notes, “real life is for March.”