Personalized Most Wonderful Time Toddler Long Sleeve T-Shirt. It's The Most Wonderful Time of the Year! Festive holiday sentiment celebrating the season. Happy Holidays and Merry Christmas! 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.