Episodes built around special observances like Christmas and Halloween are irritatingly common in the sitcom world. But NBC’s late, lamented 30 Rock found some virgin holiday territory with an episode called “Leap Day” back in 2012. Directed by Steve Buscemi, this installment of the sitcom’s penultimate sixth season centers entirely around February 29, that magical extra day added to the calendar as a corrective measure every four years. In 30 Rock’s surreal alternate reality, Leap Day is a beloved, widely celebrated holiday with its own color scheme, rituals, and mythology. Instead of Santa Claus or the Easter Bunny, the spirit of February 29 is embodied by the jolly, mustachioed Leap Day William, who emerges quadrennially from the Mariana Trench to trade children’s tears for candy. Having grown up in an Amish community, befuddled protagonist Liz Lemon (Tina Fey) is alone in her ignorance of Leap Day, but she receives a crash course about the odd holiday as the episode progresses. The inspirational take-away lesson is that nothing that happens on Leap Day matters.

Part of Liz’s education comes from occasional glimpses of a fictional film called Leap Dave Williams, supposedly a cinematic classic that runs all day on USA every February 29, à la A Christmas Story. Starring Jim Carrey and Andie MacDowell, Leap Dave draws heavily on The Santa Clause, with traces of Liar Liar and Groundhog Day thrown in. Jack Donaghy (Alec Baldwin) gives Liz a brief plot synopsis: “Uptight lawyer Dave Williams turns into the real Leap Day William after an ice machine trip gone awry.” YouTuber Oscar Chamberlain has helpfully assembled a supercut of all the Leap Dave Williams scenes from the episode, giving viewers a taste of what the full-length version must be like. It’s a standard “overworked suburban guy finds redemption through supernatural means” story, except this one features the star of Ace Ventura growing hideous gills on his neck. Everything turns out for the best, though, and Carrey ends the film by running down the street and yelling, just like Jimmy Stewart in It’s A Wonderful Life. “I saved Leap Day!” he yells. “And connected with my son! And I solved the big case from earlier! Merry Leap Day, everybody!”

Meanwhile, over at Atlas Obscura, 30 Rock co-creator Robert Carlock has shared the origins of Leap Day William with writer Reyhan Harmanci. The character, Carlock confirms, was conceived especially for the sitcom and does not come from any real-world mythology, though he does draw inspiration from Santa Claus and the Easter Bunny. “We had been talking about leap day,” he says, “and this whole mythology arrived, which we loved instantly.” For the 30 Rock writers, it was “a completely untouched new Christmas.” While he doesn’t remember how Carrey and MacDowell first got involved, Carlock does say that the two actors instantly agreed to be part of the episode. And what of the strangest aspect of Leap Day William, his fish-like gills? Well, that draws on the ancient historical nature of the character, Carlock explains:

When the world changed, some of the old gods, the Vikings and the Romans and the Assyrians, some of them hid, 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.


So that explains that.