Sitting on a Nail

A man was walking down the street one day and saw an old man sitting on his porch in a rocking chair.

Next to him was a dog.

The dog was whining.

The man asked:

"What's wrong with your dog?"

The old man said:

"He's sitting on a nail."

The man asked:

"Then why doesn't he get off it?"

The old man rocked back and forth for a moment.

Then he said:

"I guess it doesn't hurt bad enough yet."