Personalized Happy Pi Day Math Symbol Pirate Youth T-Shirt. Funny happy Pirate Day Pi symbol math Youth T-Shirt - White has cute green pi wearing an eye patch for students or teachers. Let the good times roll in a durable T-Shirt that takes kids from school to play in an amazing array of colors. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar.