Personalized 1st Birthday Kitten Blue Toddler Long Sleeve T-Shirt. I'm one! A cute blue kitty cat has a birthday hat and a cupcake with a 1 shaped candle. Happy 1st birthday to 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.