Personalized 3rd Birthday T-Rex Toddler Long Sleeve T-Shirt. A grinning T-Rex dinosaur holds a birthday cupcake and wears a party hat to celebrate the three year old's 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.