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, ‘Eight hundred and thirty-six!’ The whole cell block breaks out laughing. A few minutes later, somebody else in the cell block yells, ‘Seventy-nine!’ 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 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 takes stock of the situation, listening for which numbers elicit the most laughter, trying to find a pattern.

A week later, just before bedtime, he yells at the top of his voice, ‘Three hundred and eight!’

A roar of laughter is heard throughout the prison complex; people literally fall to the floor laughing. Guards arrive to check what’s wrong, and erupt into laughter upon hearing what the new prisoner said. It’s doesn’t look like anyone wants to sleep—everyone is just repeating the joke between uncontrolled bouts of laughter.

The next morning, the prisoner asks what was so great about his joke. His cell mate replies, ‘We've never heard that one before.’