After retiring, Mr. Johnson moved into a condo near the ocean. Every morning, while he ate his breakfast, he would look out the window at the ocean.
Almost every morning, Mr. Johnson saw a young man sitting on the dock, fishing. It didn't matter if the weather was good, so-so, or downright terrible. The fisherman seemed to go to the dock every morning.
After he had lived in his condo for a few months, Mr. Johnson noticed something. Some mornings, the fisherman would sit on the left side of the dock. Other mornings, he would sit on the right side. And on still other mornings, the fisherman would sit at the end of the dock. There didn't seem to be a pattern to this. Mr. Johnson wondered how the fisherman decided where to sit when he went fishing.
One morning, Mr. Johnson decided he would find out. He got dressed, and without eating his breakfast, left the condo and went to the dock, arriving there at the same time as the fisherman.
"Excuse me, sir," Mr. Johnson said to the fisherman. "I've noticed that sometimes you fish from the left side of the dock, sometimes you fish from the right side of the dock, and sometimes you fish from the end of the dock. How do you decide where to fish from?"
"Well," said the fisherman, "every morning, I wake up and look at my wife. If she's lying on her left side, I fish from the left side of the dock. If she's lying on her right side, I fish from the right side of the dock. If she's lying on her stomach, I fish from the end of the dock."
"That's an interesting method," said Mr. Johnson, "but what if she's lying on her back?"
The fisherman looked slyly at Mr. Johnson and said, "On days like that, you don't go fishing."