A bunch are sitting around in prison

One guy shouts, “Six-hundred and eighty-eighty!” Everyone bursts into laughter.

As the laughter’s dying down, another guy shouts, “Eleven-hundred and twelve!”

Uncontrollable laughter. Another guy chimes in with, “Three hundred and forty-five!”

Everyone doubles over, hysterical. The new prisoner doesn’t get it and asks the guard. “Well,” the guard says, “In the prison library, there’s an encyclopedia of the world’s greatest jokes.

Each joke has a number. Most of the guys have it all memorised, so, instead of going through the whole long joke, they just say the number.

The new prisoner thinks that’s great and wants his turn. He figures there must be a number 50, so, he shouts, “Fifty!”

Dead silence. He turns to the guard, “No one laughed.”

“You have no idea how to tell a joke.”