ok, before everyone starts yelling repost, calm down for a minute. I know there have been threads about this movie before, mainly just telling people to see it, blah blah. I've watched it twice now and I still don't know WTF is going on.

So if anybody could explain IN GREAT detail, exactly WTF happens in this movie, that would be awsome. I guess here is as good as anyplace for a spoiler warning, if you haven't seen the movie, you prolly should not read the replies to this (assuming I get any) PLEASE make sense of this for me.