A new prisoner was assigned to a cell. On the way, he heard one prisoner say: “110!” The other prisoners laughed really hard.
Then another prisoner said: “93!” The prisoners laughed again.
When he arrived at his cell, out of curiosity he asked his cell mate why the other prisoners said numbers then everybody laughed.
His cell mate explained that the prisoners have heard plenty of jokes over and over again, so they decided to number them to make retelling them really easy.
Just after that, the new guy shouted loudly: “153!”
The whole cell block laughed extremely hard, until tears came down from their eyes.
His cell mate replied: “Hilarious mate! We’ve never heard of that one before!”