A man is sent to prison for the first time.
The first night there, after the lights in the cell block are turned off, he immediately sees his cellmate going over to the bars and yelling, "twelve!"
The whole cell block breaks out laughing. A few minutes later, somebody else in the cell block yells, "four!" Again, the whole cell block breaks out laughing.
"Why are you guys just yelling numbers?" He asks his cellmate. "What's so funny about random numbers?"
"Well," says the older prisoner, "They're not random. It's just that we've all been in this here prison for so long, we all know all the same jokes. So after a while we just started giving them numbers and yelling those numbers is enough to remind us of the joke instead of telling it."
Wanting to fit in, the new prisoner walks up to the bars and yells, "SIX!" But instead of laughter, a dead silence falls on the cell block. He turns to the older prisoner, "What's wrong? Why didn't I get any laughs?"
"You didn't tell it right."