One day when the teacher walked to the blackboard, she noticed
someone had written the word 'PENIS' in tiny letters. She turned
around and scanned the class looking for a guilty face. Finding
none, she quickly erased it and began class. The next day, she
went into the room, she noticed in large letters the word 'PENIS'
again, this time written about halfway across the board. Again
she looked around in vain for the culprit, so she proceeded with
the day's lesson. Every morning, for about a week, she went into
the classroom and found the same disgusting word written on
the board. Each day the word was written larger than the
previous day. Finally one day she walked in expecting to be
greeted by the same word on the board but instead she found
the words: "The more you rub it, the bigger it gets."
