Personalized I'm Six Years Old with Dog and Mouse Long Sleeve Creeper. Celebrate your birthday with Dog and Mouse, the unlikely best friends from the children's book "Dog and Mouse" by Michelle Nelson-Schmidt. I'm Six Years Old with Dog and Mouse Long Sleeve Creeper - Natural, perfect for young readers, helpers, and great friends on their birthday. For chillier weather, dress baby in this soft long sleeve creeper in a great fitting 1x1 baby rib. 5.0 oz., 100% combed ringspun cotton, 1x1 baby rib. White is sewn with 100% cotton thread, Flatlock seams, Double-needle stitched rib binding on neck, shoulders, sleeves and leg openings,Reinforced three-snap closure on binding.