The correct answer is:
It´s an example to show the seriousness of cheating.
Paul Feldman, the Bagel Man mentioned in Freakonomics by Levitt and Dubner, is a man who started his own business selling bagels. He started leaving bagels in an office building, next to a box with a hole in the top and a sign requesting clients who took a bagel to leave money in return.
His statistics about how often people stole bagels is used as an example of white collar crime.