Personalized So Cute Birthday Youth T-Shirt. Cute birthday Youth T-Shirt - Black with colorful sprinkles and I'M SO CUTE IT MUST BE MY BIRTHDAY saying. For the birthday boy or girl. 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.