1 | Galentine's Day, Parks and Recreation (Feb. 13)

Parks and Recreation protagonist Leslie Knope (Amy Poehler) is incredible at gift-giving and showing the people in her life how much she appreciates them, and Galentine’s Day is just one example of how she does it. In a Season 2 episode named after the holiday she created, Leslie hosts a party on Feb. 13—the day before Valentine’s Day—to toast her female friends. Since 2010, the event has taken on a life of its own, with women planning special outings and giving out thoughtful presents to each other. Because, in a world where romantic relationships seem to get all the attention, it’s important to take the time to honor your friendships, too!

2 | Leap Day, 30 Rock (Feb. 29)

The Tina Fey sitcom didn’t invent Leap Day, but it definitely made it a whole lot weirder. That’s mostly thanks to the addition of Leap Day William, a character Kenneth (Jack McBrayer) swears is a popular cultural figure who lives in the Mariana Trench and “emerges every four years to trade children’s tears for candy.” You’ll know him by his blue suit, visible gills, and sharp fangs. Unfortunately, your celebration can’t include a screening of the beloved Leap Day romance starring Jim Carrey and Andie MacDowell—that's another bizarre 30 Rock creation.

3 | Rex Manning Day, Empire Records (April 8)

The deliciously ‘90s record store dramedy takes place over the course of a single day—the most important day in history, in fact. It’s the day when fading heartthrob and Class-A jerk Rex Manning (Maxwell Caulfield) is scheduled to do an in-store signing, and all hell breaks loose among the 20-something staffers. So on April 8, sing a verse of “Say No More, Mon Amour,” break out your flannel, and come clean to your crush: It’s Rex Manning Day!

4 | The Perfect Date, Miss Congeniality (April 25)

In the Sandra Bullock comedy Miss Congeniality, Miss Rhode Island (Heather Burns) misunderstands (or does she?) a pageant interview question about what she considers to be the perfect date. She barely even hesitates, dubbing April 25 the winner, “because it's not too hot, not too cold” and “all you need is a light jacket.” No matter the weather wherever you are in the world, you’ll find Twitter flooded with memes on Rhode Island’s favorite day of the year, and possibly catch a cast tribute or two.

5 | Star Wars Day (May 4)

Fans of puns, this one's for you. May 4 isn’t a special date in the Star Wars canon—or maybe it is, and we just can’t tell because our heroes use the Galactic Standard Calendar instead of our own—but rather a play on the frequently uttered phrase, “May the Force be with you.” The official Star Wars site notes that the holiday was created and should therefore be owned by fans, but you can usually look forward to the powers that be releasing exclusives and mashups to mark the occasion.

6 | Freedom Day, Futurama (July 4)

A Season 4 episode of the animated series Futurama introduced this holiday, during which anyone can do pretty much anything they want without any repercussions. Unfortunately for fans, there’s no such day in this reality, so they’ll never really be able to fully celebrate. But Freedom Day—which evidently evolved from the Fourth of July—may be a good excuse to take a risk or try something new, just like Dr. Zoidberg (Billy West).

7 | Federation Day, Star Trek (Aug. 12)

In 2161 in the Star Trek universe, the Articles of the Federation were signed, and the Federation of Planets (the galactic-level government first introduced in the TV series) was officially born. There isn’t 100 percent agreement on the exact anniversary—different pieces of Star Trek media list different dates—but most of the fandom celebrates Federation Day (and their favorite sci-fi franchise) on Aug. 12, based on the word of a few tie-in novels.

8 | Mean Girls Day (Oct. 3)

On Oct. 3, Aaron Samuels (Jonathan Bennett) asked Cady Heron (Lindsay Lohan) what day it was, and Mean Girls Day was born. The 2004 comedy—about a teen who grew up in Africa navigating the perilous social minefield of the American high school experience—can be quoted verbatim by many of its fervently dedicated fans, so it’s no wonder they latched onto a somewhat official date on which to celebrate it. Festivities can include wearing pink (even if it’s not Wednesday), judging your friends, creating new slang (“fetch” could still happen!), and, of course, rewatching the modern classic.

9 | Chrismukkah, The O.C. (Dec. 10)

As the child of a Jewish father and a Christian mother, The O.C.’s resident geek Seth Cohen (Adam Brody) founded a holiday that would bring his whole family together. Chrismukkah is, of course, a combination Christmas/Hanukkah celebration that incorporates elements from both traditions... as well as the music of his favorite band, Death Cab for Cutie. While Seth’s idea doesn’t really take off in his own world, it blew up in ours, giving families and friend groups of different faiths a name for their inclusive observation. Chrismukkah is celebrated on the first night of Hanukkah or Christmas Eve—whichever comes first—so in 2020, this holiday falls on Dec. 10.

10 | Festivus, Seinfeld (Dec. 23)

Most of us learned about Festivus from the Season 9 Seinfeld episode, “The Strike,” in which it’s revealed that George’s father (Jerry Stiller) came up with it in protest of the stress of the holiday season. But Festivus was actually invented by the father of Seinfeld writer Dan O’Keefe, and annually celebrated by their family. Thanks to the cynical sitcom, people all over the world now hold Festivus in their hearts every Dec. 23. If you want to mark it properly—and per the show’s guidelines—you’ll need to display the Festivus pole and host a Festivus dinner, capped off by the Airing of Grievances (in which you tell your loved ones all the ways they let you down in the past year) and the Feats of Strength. If you’re lucky, you may even experience a Festivus miracle or two.