Personalized This Kid is 4 Birthday Toddler Long Sleeve T-Shirt. This kid is Four! Celebrate your child's fourth b-day with this cute thumbs up 4th design. Happy Birthday 4-year-old! 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.