A Stroll in the Park

Murphy and his wife, a middle-aged couple, went for a stroll in the park. They say down on a bench to rest. They overheard voices coming from a secluded spot. Suddenly Mrs. Murphy realized that a young man was about to propose. Not wanting to eavesdrop at such an intimate moment, she nudged her husband and whispered:

- Whistle and let that young couple know that someone can hear them.

Murphy said:

- Whistle? Why should I whistle? Nobody whistled to warn me.