The back cover of J for C Programmers says of the front cover,
David's watch was not working. He remembered passing a little shop with clocks and watches in the window, so he took the watch in for repair.
"Can I help you?" asked the man behind the counter.
"I want this watch repaired," said David.
"I'm sorry. I don't repair watches."
"Well, how much for a new one then?" asked David.
"I don't sell watches."
"You don't sell watches?"
"No, I don't sell watches."
"Clocks, you sell clocks then? How much for a clock?"
"I don't sell clocks."
David was getting exasperated. "You don't sell watches, you don't sell clocks?"
"No, I'm a mohel [a person who does circumcisions]," replied the man.
"Then why do you have all those clocks and watches in the window?"
"If you were a mohel, tell me, what would you put in your window?"
Anyway, I thought it would provide better entertainment than most things I could put there.