Personalized Little Elf 3rd Birthday Youth Long Sleeve T-Shirt. Youth Long Sleeve T-Shirt - White for a little elf's 3rd birthday with a polka dotted number 3 and snowy striped North Pole sign. Perfect for Santa's helper on his or her Christmas birthday. youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)