Personalized Monkey First Birthday Toddler Long Sleeve T-Shirt. It's my first birthday! This cute little monkey is celebrating his 1st bday! Happy birthday 1-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.