At school, a boy is told by a classmate that most adults arehiding at least one dark secret, and that this makes it veryeasy to blackmail them by saying, "I know the whole truth"even when you don't know anything.The boy decides to go home and try it out. As he is greetedby his mother at the front door he says, "I know the wholetruth." His mother quickly hands him $20 and says, "Justdon't tell your father."Quite pleased, the boy waits for his father to get home fromwork, and greets him with, "I know the whole truth." Thefather promptly hands him $40 and says, "Please don't say aword to your mother."Very pleased, the boy is on his way to school the next day,when he sees the mailman at his front door. The boy greetshim by saying, "I know the whole truth." The mailman dropsthe mail, opens his arms and says, "Then come give yourFATHER a big hug."