When I was very young, somewhere in elementary school, I once had the dream that I woke up in my bed. I then went to the bathroom, looked myself in the mirror, and said "I'm dreaming." I then went back to bed. I then woke up again, went to the bathroom, looked in the mirror, and said "I'm still dreaming." I then woke up for a third time, went to the bathroom, looked myself in the mirror, and assured myself I had finally woken up.