A new guy arrives in prison, is introduced to his cellmate, and tries to settle in. At mealtime, the two take their places at the mess hall.
Just when the new prisoner starts on his chow, he hears another prisoner shout, "22!" Everyone bursts into laughter spontaneously.
A few minutes later, another prisoner calls out, "36!" The prisoners are besides themselves, practically rolling in the aisles.
"What's going on here?" asks the new prisoner, turning to his smiling mentor.
"Well, we only have one joke book in here. After so many times of retelling, everyone more or less knows them all by heart. Now, when someone wants to tell a joke, all he does is mention the number of the joke. Everybody remembers the joke, and they laugh just as hard as if it was told the first time."
"I see," replied the new prisoner. "It is a curious custom, but I suppose it does save time."
Soon, the new prisoner got hold of the book, and starts to memorize some of the jokes. At the next opportunity, he screws up his courage to tell his first joke for the lunchroom crowd.
"53!" he called out with all the vigor he could muster.
There was absolute silence in the hall. Chagrined, he turned to his cellmate buddy to ask why no one laughed.