As mentioned, electric fans and fan death have been around in Korea since the 1920s.
Filming is hard, and the income is low.
The idea is taken from online gaming where levels signify the skills and expertise of your character.
Now, I hope you have a cup of tea handy and maybe a blanket to hide behind.
It would probably be about 4 a.
The guy at emart went to great pains to explain how dangerous the fan can be when sleeping.