Personalized When I Grow Up I'm going to Change the World T-Shirt. When I Grow Up I'm going to Change the World T-Shirt - Red. Your little boy may change the world some day! Why not show it off to your family and friends and prove yourself right later on? 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.