Is it normal to wonder what having my head up my ass would feel like?

Lots of people use the term "he has his head up his ass" to describe someone they think is a moron. They do this often and I have nothing against it. I've seen the movie Hancock and in one of the scenes Hancock shoves a man's head up another man's ass. All this got me wondering, what would that actually feel like? Obviously there would be a fair amount of pain in the rectal area, and probably some internal damage. Then there is the amount of flexibility required. Basically you would have to be a yoga master. Anyone else wondering about this? To be clear, I don't actually have any desire to do this. Just curious.