My grandmother told me when she was in high school an old math teacher in his 60’s named Harold Davidson was teaching math and one of his students wouldn’t stop tapping his pen during class. The teacher went berserk and lost his mind. He snatched the pen and attacked the kid, lodging the pen down the child’s throat while his classmates looked on screaming. While struggling, the kid kicked the teacher in the chest with the little energy he had left. The teacher collapsed and they both died at the same time.
When school was back in session and math class began with the new teacher, the class noticed that a weird symbol appeared on the chalk board. The symbol had lines inside of a circle. All the lines within the circle were the common math symbols = + x and division. If you outline certain parts of the symbol it looks as if a pacman shape has a line going through its mouth or maybe a head getting choked with a pen. The teacher asked who drew it but no one came forward. The teacher laughed it off and tried to erase it off the board but she couldn’t remove the mark.
She decided to live with it and ignored it for a month, but since maintenance couldn’t even remove the symbol she began to get annoyed. Eventually she got the whole chalkboard replaced. As the students arrived for their next math lesson they were shocked to find the new teacher dead laying in the exact same spot wear Harold died. The autopsy found the teacher had a pen shoved down her throat.