Prison Jokes?

A man went to prison for the first time and wanted to fit in and make friends. At 10:00 the lights went out and all was quiet. All of a sudden he hears a voice yell 11. Then he hears laughter. About ten minutes later he hears 27, again more laughter. He can't figure it out.

The next day during the exercise period he asks someone what was going on. He was told they are not allowed to talk after lights out. But in the prison library there is a joke book and the jokes are listed by numbers.

He went to the library and memorized some of the jokes. He couldn't wait until lights out and try it out. At 10:00 when the lights went out, he yelled out 23. Nobody laughed. He thought about the joke and decided it wasn't all that funny. Then he tried 19. Still nobody laughed. He remembered people laughed at 27, so he yells out 27! No laughter. He asked his cell mate what happend. His cell mate said, oh well some people can tell jokes and some people can't!!!!!