Data compression

A student of information theory, on his first day at college, entered a strange and bizarre world. The only sounds were the occasional calling out of a number by one of the professors, followed by laughter. One professor would say '52', there would be a short pause then peals of laughter. Someone else says '713', same thing, everyone falls down laughing.

"What's going on here?" he asked his tutor.

"We're telling jokes," said his tutor.

"Telling jokes?"

"Yes, you see, we've all worked here so long we know each other's jokes. There are a thousand of them. So, being information theorists we applied data compression. We just assigned them all numbers, 0 through 999. It saves a lot of time and effort. Would you like to try? Just say any number 0 to 999..."

He wasn't fully convinced. But he tried. Very quietly he whispered "477".

Hardly a murmur.

He looked at his tutor. "What's wrong?" he said. "Try again," says the tutor.

So he does. "318" - same again, not a thing, hardly a murmur.

"Something's wrong," he says.

"Well," says the tutor, "it's not so much the joke as the way you tell it!"

This student eventually succeeded by accident in the most dramatic and unexpected way. He called out a number outside the range 0 to 999. "Minus 105," he said.

At first there was stunned amazement, then first one professor laughed, then another then another, till they were all rolling about holding their sides.

None of them had heard that one before.