Oh yeah, there was this once in high school. I was never the greatest when it comes to speaking in front of a bunch of people.
It was the "World History" class. I had my memo card in hand and I had prepared as prepared can be the night before, memorized everything, did the whole routine in front of a mirror. But...when I got up there in front of everyone...I just forgot everything and froze. I couldn't begin for what felt like eternity ( 2 minutes or so in reality, haha). And the rest is history. 