Personalized So I'm Little, But I'm Gonna be a Big Sister T-Shirt. There's a new sibling on the way, and that means you've been officially promoted from "Only Child" to "Big Sister." So I'm Little, But I'm Gonna be a Big Sister T-Shirt - Black, for girls who'll be getting their little brother or little sister soon. 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.