Personalized 4th Birthday Unicorn 4 Year Old Girl Toddler Long Sleeve T-Shirt. 4th birthday Toddler Long Sleeve Tee - White girls unicorn party shirt says this girl is four. 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.