Personalized Mermaid 2nd Birthday Toddler Long Sleeve T-Shirt. Mermaid 2nd birthday! A cute little mermaid celebrates your second birthday with her fish friends. Cute gift for the two 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.