Personalized 3rd Birthday Unicorn Toddler Long Sleeve T-Shirt. A pink unicorn surrounded by a colorful rainbow, next to a sunny yellow 3. Cute gift for the birthday girl's 3rd bday! 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.