In summary, there is this belief in South Korea that if you leave an electric fan on in a closed room overnight, it can kill you, supposedly by asphyxiation or hypothermia. There is not really a basis for this theory in reality, and it seems that younger Koreans are less likely to believe this theory.

Now that I think about it more, perhaps my next Halloween costume should be a Grim Reaper costume with a fan on my face.