Personalized That's right! You're my best friend! Youth Long Sleeve T-Shirt. Show off your bestie with That's right! You're my best friend! Youth Long Sleeve T-Shirt - Heather, featuring Dog and Mouse from the children's book "Dog and Mouse" by Michelle Nelson-Schmidt. youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)