Personalized 6th Birthday Cute Unicorn Youth T-Shirt. Celebrate your 6th birthday with thisYouth T-Shirt - White cute I'm 6 quote and this adorable unicorn fantasy design for a little girl. 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.