My late great old Dad used to sell Britanica (on his way out of the coal mines). One day, as he told it, he had a couple at the point of picturing their kid, not yet born, becoming president as a result of the fine set of books they were to buy. The wife realised what was up, and tried to kick the husband under the table and instead hit my dad's shin. He turned to her and said "don't worry my dear, you husband will buy the books for you!" and she was so embarassed, she did!