Personalized That's right! You're my best friend! Toddler Long Sleeve T-Shirt. Show off your bestie with That's right! You're my best friend! Toddler Long Sleeve Tee - Heather, featuring Dog and Mouse from the children's book "Dog and Mouse" by Michelle Nelson-Schmidt. 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.