Personalized Superhero 7th Birthday Toddler Long Sleeve T-Shirt. Happy 7th birthday! Celebrate your child's seventh b-day with a cool SUPER 7, superhero gift. Happy Birthday seven-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.