Pi Day is a fun holiday meant to celebrate the mathematical constant of Pi, or π. The event is observed each year on March 14, which is taken from the first three digits of Pi: 3.14. Pi Day was recognized by the U.S. House of Representatives in 2009 and UNESCO has designated Pi Day as the International Day of Mathematics in 2019. Shop funny Pi Day t-shirts here for math fans!

From Amazon

Pi Day Shirt Superhero Captain Pi Math Geeks Gift Pi Symbol Youth Kids T-Shirt X-Small Navy From Amazon

Ladies Game V-Neck Tee I Ate Sum Pi Funny Pi Day Math Teacher Shirt Black/Heathered Charcoal M From Amazon

I Ate Some Pi, and it was Tasty | Funny Delicious Math Teacher Humor Pun T-Shirt-L Black From Zazzle

Pi Pie T-Shirt