Personalized 3rd Birthday Polka Dot 3 Year Old Youth Long Sleeve T-Shirt. Happy 3rd birthday design has navy and white number 3 on a Youth Long Sleeve T-Shirt - Royal Blue for girls turning three years old youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)