Personalized Third Birthday Cat Unicorn Toddler Long Sleeve T-Shirt. Adorable kitten with unicorn horn and I'm 3 quote for a girls 3rd 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.