Personalized Monster 1st Birthday Toddler Long Sleeve T-Shirt. A cute green monster with a birthday hat is celebrating its 1st birthday! Great gift for the one 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.