Personalized Unicorn 4th Birthday Toddler Long Sleeve T-Shirt. Unicorn 4th Birthday - A pastel unicorn jumps over a colorful rainbow and smiling cloud. Cute gift for the four year old's fourth birthday! 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.