A new inmate arrives at a prison. On his first night, he hears another prisoner yell, "Number 22!", and the whole cell block erupts in laughter. A few minutes later, someone yells, "Number 45!", and again, the whole cell block howls.

Confused, the new guy asks his cellmate what is going on.

His cellmate explains, "Well, we've all been in here for so long, and we know all the same jokes by heart. To save time, we numbered them, so we just shout the number instead of telling the whole joke!"

Excited to fit in, the new guy stands up on his bed, takes a deep breath, and shouts, "Number 72!"

Dead silence. Nobody laughs.

Confused and embarrassed, he sits back down and asks his cellmate what went wrong. "Was Number 72 not a good joke?"

His cellmate sighs and says, "Oh, 72 is one of our absolute favorites!"
The new guy asks, "Then why didn't anyone laugh?!"
The cellmate shrugs and replies, "Some people just don't know how to tell a joke!"