rolling rolling rolling

As a dog owner I am confident that you have often wished your dog could talk. Why do you run zoomies after a poop? Why do chew my shoe when you have three chew toys lying next to you? How come you don't like that dog? They seem perfectly fine to me.

Today's question I would like to ask is, "why do you love to roll on your back?"
He loves to do this and does it every morning and usually in the afternoon.
Some photographic evidence.



It seems to feel really good but often there is more to it than that - he looks at you while upside down with this quizzical look. Then stands up and shakes his head flapping his ears enthusiastically. I don't know what it is all about but I would like to know.