Personalized 1st Birthday Unicorn Kitty T-Shirt. Adorable rainbow unicorn kitty celebrates your baby's 1st birthday. I'm One! Cute first birthday gift for your one year old. Everyone loves our Custom T-Shirts! Wardrobe essential for looking good, 24/7. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar. Shoulder-to-shoulder taping. Double-needle stitched sleeves, bottom hem and front neck. Note: greys are a cotton/polyester blend.