Imagine you get in an elevator and as soon as you hit the button for your floor, the lights flicker.  They come back on and things to appear to go back to normal.  Then suddenly, the bottom drops out!

Suddenly the floor panels appear to be falling down the elevator shaft.  The only thing is that you are still standing in an elevator that looks like it has no floor.  That would be enough to make me pass out.  I get nervous enough when elevators make clanging and banging noises as they are ascending and descending.  If this happened, they would have to clean the elevator after I got off!