I know LOADS about colonic irritation as well, much more than could be gleaned from websites, but I ask you, why do you want to lay in a grotesque foetal position and have a tube pushed up your bum? Your intestinal tract is very good at taking care of itself, why upset it by poking things up it?
Do you or do you not fancy a tube stuck up your bum?
God designed the mechanism to work perfectly well in a general mouth-to-bum direction and I can't see why you would wish to interfere, also paying to give several people a huge laugh to boot.