Oh, I totally forgot!! We buy lots of coke (coupla soda addicts here), and lots of times buy the twelve packs that can fit in the fridge. Neither of our babies can really fit in there, but they LOVE to run across the room and forcefully shove themselves into it, with the other one on the outside, at the back, and the back of the box has an opening of about a half-inch, so they can JUST fit their paws through and play like they don't know it's one another! It's so funny to see them dive into these boxes, like they're as small as they were when they were first playing with them at about a month old!! LOL!!
Another small offshoot of the box-playing, of course, is the whole drawer play idea. Our old place had a built-in dresser in the hallway, and they LOVED getting into the drawers, whether to play or to sleep. We didn't like it so much because our clothes were in there, but no matter what we did to try to keep them closed, they always found a way to open them again. Goofballs!!