Personalized Big Sister Unicorn Toddler Long Sleeve 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! A classic for Fall, Winter and Spring, these long sleeve toddler t-shirts are sure to be a staple in your child's wardrobe. Whether layered or alone, this t-shirt is soft yet durable enough to stand up to your toddler's playtime demands.