Personalized 1st Birthday Kitten Youth T-Shirt. I'm one! A cute kitty cat has a birthday hat and a cupcake with a 1 shaped candle. Happy 1st birthday to the one-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.