Sadie used to like to prop herself up between pillows on my bed:
Here are 2 of my favorite belly-up pictures of Spencer. As a small pup, he would just collapse any old place. Throughout his life, I always used to think he spent more time belly-up than right side up. Only in his later years when arthritis set in did he stop laying this way. I always used to think they were dreaming of belly rubs, or maybe they wanted to be ready in case someone would come who wanted to give them one.
From baby Annie up til now...I think it's her favorite way to lay. When I find her like that in her crate at night I get a feeling of accomplishment, like I did enough to make her super tired. I give myself too much credit LOL.
Both of mine love to lay like this too! I'll try and get pictures of them but especially of Doppler. For some reason he prefers to lay against the wall in the hallway on his back. He uses the wall for support it seems. It's pretty funny.