edNational Monkey Day is celebrated every December 14th. It is a day dedicated to recognizing and appreciating all species of monkeys around the world.
The day was founded by Shope and Casey Seltzer in 2000, who created the holiday to honor their pet monkey, Heidi. Since its creation, the holiday has grown in popularity and is now celebrated in a variety of ways, such as sharing photos of monkeys and theorizing why their evolutionary cousins, humans, have taken over the world.