I always thought saying "God bless you" when someone sneezes was a strange superstition. It stems from the old-timey belief that sneezing can temporarily let your soul slip out of your body. In this brief moment the devil can come and snatch it up. Blessing the person will, of course, discourage/scare off the devil and you'll be fine. Don't say it and woh! look out, you're just asking for trouble.
Shouldn't your soul be harder to remove? Like in Mortal Kombat 2?
I thought it was that they thought you sneezed and you blessed them it was because there was a demon you where trying to get out, and they wished you blessed to get it out. It's the same basically.
I hear in koria they also think that if you leave a fan on all night you well run out of air and die.