A crazy old crackpot who usually shows up during math class.
Yo, man, I was in math yesterday, and this freaky looking old lady came in, knocked on my desk, gave me a creepy stare, then walked backwards out of the room. She waited outside the door for like 5 whole minutes, and then just left. She comes in like, every second math class. I heard her name was like, Beryl Woodsworth or something.