December 14th is Monkey Day. The unofficial holiday was started in 2000 when founder Casey Sorrow jokingly scribbled Monkey Day on a friend’s calendar, and first celebrated by Lansing residents and art students at Michigan State University. It gained notoriety when Casey’s comic strip, Fetus-X, began promoting it online. Since then, Monkey Day has been celebrated internationally with costume parties and contests. We celebrate by spanking the monkey. JK. NOT REALLY. To celebrate, we corralled a pack of pretty hilarious monkey pics. Check ’em out below.