Definitely the wrong kind of fan and not about fun...
You can read all of the books and web sites you want about a foreign culture, but chances are that you'll find the reality will catch you off guard sooner rather than later. One day, you'll be talking about the summer heat and how to best cope with it and a student will say that it's just too cold using the air conditioner all night. Rather reasonably, you'll suggest using an electric fan. This will often elicit a wide-eyed look and you'll be told that you shouldn't use a fan while you sleep because you might suffocate. I've told students time and time again that, when I lived in the U.S., I slept all night with a fan in my window and lived to tell the tale, but they still are too superstitious to use one themselves. Sweating the night away is preferable to risking having all of the breathable air sucked out of their lungs by a demon apparatus.
I'll miss the incredulous looks I get when I say I sleep with an electric fan running and hearing that I'm flirting with death by doing so.