My smaller dog, Speak, fits completely under our couch when he lays on his belly. He will often wiggle under there to retrieve a ball or toy. I started calling it "hiding" and now we play "hide and seek" I can tell him "go hide" and he will wiggle under the couch with only his nose poking out. I'll wait a minute and then yell "found you!" and he comes running out to get the treat I usually have for him.

Our other dog, Mazie is just a puppy, but she has a favorite stuffed bear (it's about the size of a beanie baby) and she hides it all over the house. She shoves it on the book shelf, behind furniture, in the laundry basket, and the other day, I caught her trying to hide it in the VCR! Silly puppy.