A few days before his proctological exam, a one eyed man accidentally swallowed his glass eye. He was worried for a while, but there were no ill effects, so he forgot about it.

Once he was in the doctor's office, the man followed instructions, undressed, and bent over. The first thing the proctologist saw when he looked up the man's arse was that eye staring right back at him.

"You know," said the doctor, "you really have to learn to trust me."

This one of my favorite jokes and have never heard it told by others, but thanks for this first time experience.

My version doesn't make the guy one-eyed, after all what would be important about that issue. Second, my version includes an explanation why he swallowed his eye.

It would seem that on very dry or dust filled days, this guy would take out his glass eye and moisten it in his mouth to lubricate it. While doing so, one day he swallowed it.

Assuming it would pass through without difficulty, as it was a very expensive eye and smooth in shape the guy waited. Three days later he got terrible pains in his lower intestine and off to the proctologist he went. etc.