Personalized I'm Three 3rd Birthday Watermelon Youth T-Shirt. Cute red watermelon slice with I'm Three quote comes on this 3rd birthday Youth T-Shirt - White. 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.