because when you sneeze your soul is trying to escape and saying "God bless you" crams it back in there
-OR-
when you sneeze your heart stops for a millisecond so people say "bless you" in case you are to suddenly die, resulting in an instant pass to heaven
-OR-
people are sheep and say it because it's become common practise and everyone has forgotten why

big spider 2

You find a big spider in your bedroom. Your next move is?

I'd freak the hell out, scream and run out the room (this has happened before).

There was a big fuck-off spider in the bathroom last night that I saw out of the corner of my eye. Had to enlist the help of the father to save from it's ominous presence.

I get déjá vu all the time, it's really bloody annoying. I got it yesterday when I was typing something on facebook. For about ten seconds I was completely convinced it had happened before (the particular thing I typed and the way I typed it, not just typing on facebook because that's a depressingly regular occurrence for me) or that I had dreamed it, then the moment passed and I thought....that didn't happen.
I hate déjá vu; it convinces you you're re-living something and then mere seconds later you realise it's not happened before and can't recover that bizarre feeling you just had of complete assurance that you'd just repeated something.