So I was listening to a recording of one of my biochemistry lectures and more than halfway through it, you could hear a little kid laughing in the background.  It did not sound like someone’s cell phone or an adult laugh or a cough or some other random sound.  It sounded like a little child laughing.  My class is in a huge lecture hall in the med school.  There are no little kids around.  I have concluded that the lecture hall is haunted and the little ghost kid is laughing at our imminent doom by finals.