A little change
The patient shook his doctor's hand in gratitude and said:"Since we are the best of friends, I would not want to insult you by offering payment. But I would like for you to know that I had mentioned you in my will.""That is very kind of you," said the doctor emotionally, and then added, "Can I see that prescription I just gave you? I'd like to make a little change..."

Are caterpillars good to eat?
Johnny: Daddy, are caterpillars good to eat?

Father: Have I not told you never to mention such things during meals!

Mother: Why did you say that, Junior? Why did you ask the question?

Johnny: It's because I saw one on daddy's lettuce, but now it's gone.