Maybe he has a mental disorder?
I know it may be hard for somebody of your age to understand, but whenever people do "strange" things like that, it usually means there's some underlying psychological problem. You're the one most likely amplifying whatever problem he has by excluding and teasing him. Great job.
Says the guy that likes harrass autistic pokemon members, haha. Jk anyway Jaykins. But you're right, I'm more referring to the naturally weird people that didn't pick up on some social cues that make them stand out a little. Not so much the mentally impaired.
And Cipher we have a trenchcoat guy at our school too. I think he probably sells baseball tickets under them.