He walks like that to stop the poop from flowing out. All that stool pushing has made the anus muscles week.
Rumor has it it that he Shawshank Redemptions that stuff that trickles down his leg all over the place out the bottom of his pants but its barely noticable as it is quickly trampled
Now if you see someone in the background look like they slipped on a banana peel and fall well now you know why