Personalized Worlds Best Granddad Fathers Day Grandpa Youth T-Shirt. Granddad Youth T-Shirt - White has sports style worlds best Granddad logo for a grandfather on Father's Day or his birthday. Let the good times roll in a durable T-Shirt that takes kids from school to play in an amazing array of colors. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar.