One day, a teacher walks into her classroom to start the lesson. She walks up to the board and sees in little writing the word "penis". She thinks nothing of it and wipes it off. The next day, she comes in and sees the word "penis", only this time it"s a little bit bigger. She wipes it off again. Sure enough, the next day she comes in and sees "penis" on the board a little bigger. This proceeds until the end of the year when finally, it"s across the whole board. The teacher wonders what"s gonna happen the next day since it"s taking up all the space on the board. When she came in the next day but doesent find "penis". This time she finds written, "The more you rub it, the bigger it gets".