Koreans believe that a person may die if they are in a room with an electric fan running and all of the windows and doors are closed.
They call it "fan death."
One of my fellow English teachers (an American, not a Korean) told me about this and I didn't really believe him so today I asked one of my Korean co-teachers. Once she understood what I was talking about she told me "It is real" and dismissed everything I said so I stopped arguing about it.
This is by far the strangest thing I have learned about Korean culture so far.