Personalized Superhero 6th Birthday Pink Youth T-Shirt. Happy 6th birthday! Celebrate your child's sixth b-day with a cool SUPER 6 superhero party. Happy Birthday six-year-old! 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.