There is nothing quite like coming out of a deep sleep completely startled. I have a friend I use to wake up by hovering over and staring at his face as he was just starting to come to. I guess there is something immediately frightening about having someone standing over you crazy-eyed looking at you when you are just regaining consciousness. He would jump out of bed with fear in his eyes and arms swinging. Heh, sorry Chucky if you’re out there somewhere.
I can’t think of a specific time I myself was startled out of sleep, other than on airplanes. For some reason I drift off into a deep sleep and then violently wake up for no apparent reason, with drool running down my face, and it always seems like everyone is staring at me and I’m quite sure I must have been saying some questionable stuff in my sleep.