Personalized Twins 1st Birthday Bears Youth Long Sleeve T-Shirt. Two little teddy bears are having a birthday picnic to celebrate turning one. It's Our 1st Birthday quote for twins comes on Youth Long Sleeve T-Shirt - White. youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)