My six year old daughter has had a loose tooth for some time now. When I wiggled it for her, she paniced slightly, not wanting it to be pulled. Last night, the tooth finally worked itself loose enough to pull. So when I offered her a dollar if I can pull it, on top of what the Tooth Fairy would bring her, she agreed.
A quick tug later, we both walked away, feeling richer than we had before. I had my fatherhood memento and she had a new, crisp one dollar bill in her hand. She soon doubled that by putting the tooth under her pillow and another dollar appeared that morning. The magic of the free market at work.