Personalized 3rd Birthday Monster Toddler Long Sleeve T-Shirt. 3rd birthday monster. A cute monster holds a bright yellow balloon to celebrate the three year old's third birthday! Great gift for your little monster! 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.