Vision Problems

“In my case,” said the student to the sex researcher, “when I get it part way in, my vision blurs. And when it’s all the way in, I can’t see a thing.”

“Now, that’s a most interesting optical reaction that may well have anatomical as well as physiological basis,” the researcher replied. “If you don’t mind young man, I should like to have a look at it.”

So the student shrugged and stuck out his tongue.