The joke about the prisoners who have become so accustomed to the jokes they tell so that they simply tell them by calling out each joke by number harkens back, I suppose, to just about everybody's childhood:

A prisoner, new to a particular cell block, was surprised to discover that his fellow inmates passed much of their day by calling out numbers, after which they would laugh heartily for a few moments. Every few minutes an inmate would call out a number and everyone would laugh, and then, after a few moments of silence, someone else would call out a number, and once again laughter. The inmate asked one of the other inmates whom he'd come to know to explain this strange behavior to him.

"It's simple", came the reply. "We know all of our jokes by heart, and there's really no reason to tell them at lenght. Instead, we simply call them out by number."

Though this was strange to him, the new inmate thought he'd join in on the fun. After a few weeks listening to the jokes, he took some initiative and called out "number 27!". But nobody laughed. This seemed very strange to him, since he'd heard others call out that same number, with everyone laughing afterwards. After waiting and waiting, with still no laughter, he finally asked: "why is it that when others call out that joke you laugh, and when I called it, nobody laughed?".

The reply promptly came: "You told it wrong".