You wake after a wild night of partying to find that while you were wasted, for some reason, you had a crude smiley face tattooed on your foot. You simply write it off as a lesson to never drink that much again.
The next day when you wake up, however, you discover that the face is now on your ankle, and it is not as crudely drawn.
The day after that, it is on your lower leg, and it is starting to look more like a drawing of a real face.
As it continues to move up day after day and become more realistic looking, you begin to wonder what will happen when it reaches your own face.