There was once an English teacher at my high school who was notorious for thinking cats lived in the ceiling or something. I never had her class, though, so I can't say if there's any truth to that.

But there was this one man who substituted at my high school a lot and still does, I think. He likes to tell stories about alligators, passing gallstones, surviving aneurisms, and the like, in detail. It's impossible to get any work done with him around.