Personalized Big Sister Unicorn T-Shirt. Big Sister Unicorn - A cute big sister unicorn prances with a heart on her cheek in a rainbow filled sky. Cute gift for any big sis! 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.