The shoe salesman said to the difficult customer, "Madam, I have shown you all the pairs of shoes that are on display in this store but you don't seem to like anything. What is it that you are looking for?"
The lady, ignoring the salesman's question, pointed out to a box and said, "What is there in that box? You have not shown it to me yet."
The salesman replies, "Madam, please have mercy on me. That is my lunch box."