Personalized Its My 5th Birthday with The Whatif Monster Long Sleeve T-Shirt. There's no day like your birthday, so why not try something new? It's My 5th Birthday with The Whatif Monster Long Sleeve T-Shirt - White, perfect for little fans of "Jonathan James and the Whatif Monster" by Michelle Nelson-Schmidt. Pre-shrunk 100% cotton 6.1 ounce long sleeve t-shirt. Double-needle stitched neckline and sleeves. Quarter turned. Shoulder-to-shoulder taping. Adult: S, M, L, XL, 2XL, 3XL