What do you remember???

So, in my post-before-last, I responded to a comment that Amber made and it totally made me think about moments in my life when I subconsciously realized that I was going to know something about that moment for the rest of my life... Like the whole cover art thing... what I want to know is this... Tell us all a moment when you 'knew' something... a moment that you knew when it was happening that you were going to remember it for the rest of you life...