The snowmen are getting their Halloween costumes ready for the latest board book in this New York Times bestselling series. Look for the hidden image on every page!Have you ever built a snowman and discovered the next day that his grin has gotten a little crooked, or his tree-branch arms have moved? And you've wondered . . . what do snowmen do when we're not watching?After an early snowfall, a few kids build some snowmen before going trick-or-treating. And when the kids go of