When Kip was a puppy, he loved to hide out under my bed. The bed was in the corner of my room, and he would get all the way under the farthest back corner of the bed and lay flat on his belly. I guess he felt safe and protected under there. He would eventually come army-crawling back out; I'd hear his little nails scratching on the carpet, pulling himself out. It was also his hiding spot whenever he got ahold of something he wasn't supposed to have; he'd run off with whatever and go scooting under that bed. It was both adorable and infuriating.
He's long outgrown fitting under the bed, but he still likes to squeeze himself into confined places. One of his favorite places is under our table; we call it his "fort."