What is the scariest experience you've ever had in your life? (It can be anything)

I don't know what I'd consider as the most frightening experience of my life. Having severe panic attacks is definitely high on the list; so is flying in airplanes. So were some of the dreams of Hell I had when I was more into religion as a teen. I don't think I have a specific experience that made me almost crap myself and die of fright. But I will say that fear plays a great factor in the way I live and in the way I think and feel. It is also why I love to write the things I write.

So, what I want to know is what in your life terrified the pants off YOU....