Personalized Grandpa's Sweetheart Youth Long Sleeve T-Shirt. Youth Long Sleeve T-Shirt - White with lots of hearts and pretty pink text that says GRANDPA'S LITTLE SWEETHEART. Perfect for Valentine's Day. youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)