Personalized Pi Day Funny Math Pie Slice Toddler Long Sleeve T-Shirt. Funny every day is a good day for pie Pi Day Toddler Long Sleeve Tee - Black math shirt. A classic for Fall, Winter and Spring, these long sleeve toddler t-shirts are sure to be a staple in your child's wardrobe. Whether layered or alone, this t-shirt is soft yet durable enough to stand up to your toddler's playtime demands.