Personalized I'm Three Comic Book Youth T-Shirt. Pow! Cool! Ka-Boom! I'm Three! Cool comic book style birthday gift for any three year old superhero's 3rd 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.