Personalized PopPop Grandfather Toddler Long Sleeve T-Shirt. Tell your grandpa he is number one with this fun No1 PopPop design. 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.