Personalized 6th Birthday Penguin Youth T-Shirt. 6th Birthday Penguin Youth T-Shirt - White with snowflakes and number 6 can be personalized as you order. 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.