A new jail warden was being shown through the jailhouse by the old warden.
Soon, after making rounds around the rest of the jail, they get to the cafeteria. In one corner, he sees a group of elderly men laughing hysterically.
Interested, he watches them while the older warden gets his food. One of the men shouts out "63!" and the entire table bursts out laughing. The new warden is totally baffled by the behavior of them. "74!", again a chorus of guffaws ring out.
The old warden comes back to the table where the new warden sits staring, and the new warden asks "What are those elderly men doing."
The old warden smirks, and says, "Oh, those are the life timers. They've been in here so long, they just number their jokes."
Meanwhile another one calls out "2!". Nobody laughs.
The new warden leans over and asks, "What happened?" To this the old warden replied, "Some people just can't tell a joke."