A man is sent to prison for the first time. At night, the lights in the cell block are turned off, and his cellmate goes over to the bars and yells, "Number twelve!" The whole cell block breaks out laughing. A few minutes later, somebody else in the cell block yells, "Number four!" Again, the whole cell bloock breaks out laughing.
The new guy asks his cellmate what's going on. "Well," says the older prisoner, "we've all been in this here prison for so long, we all know the same jokes. So we just yell out the number instead of saying the whole joke."
So the new guy walks up to the bars and yells, "Number six!" There was dead silence in the cell block. He asks the older prisoner, "What's wrong? Why didn't I get any laughs?"
"Well," said the older man, "sometimes it's not the joke, but how you tell it."