Personalized Coolest Trombone Player Toddler Long Sleeve T-Shirt. A snowman trombone player wearing a music note scarf with the text The world's coolest trombone player is a humorous music design for Christmas and the winter holidays. 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.