Personalized T-Rex Dinosaur 5th Birthday T-Shirt. A grumpy, purple T-Rex wearing a birthday hat sits and eats a birthday cupcake. Cute 5th birthday gift for your little five 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.