Personalized Life's Ducky 4th Birthday T-Shirt. 4th birthday LIFE'S JUST DUCKY WHEN YOU'RE 4 T-Shirt - Light Blue with adorable baby duck. 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.