Personalized Blue Monster 1st Birthday Toddler Long Sleeve T-Shirt. A blobby blue monster holds a yellow balloon and wears a bright birthday party hat as it celebrates the one year old's 1st 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.