Nothing as scary as some of the people have mentioned.
The moment of terror I remember most vividly is when I helped my mom reverse park the car in our garage. I was about.. 13 I think. The car didn't have any parking sensors, so it was my job get out and stand behind the car to make sure it wouldn't hit the work desk at the end of the garage (it was a narrow garage, I couldn't stand to the side of it without getting my toes run over). I'd shout stop when the car was in far enough and that would be it, nothing special.
I don't know what happened that day, maybe she was distracted or something, but the car didn't stop. It just kept going further back, pushing me against that desk and squeezing my organs. At first I shouted louder, thinking she didn't hear me, but the car kept coming and by then it was too late to get out of the way. I ended up frantically hitting the rear window, shouting as loud as I could. In my mind the car was broken and would crush me against the edge of that desk. I thought I was going to die right there, getting killed by some freak accident. With just almost no room to spare the car finally stopped and drove forward.
Afterwards my mother said something along the line of "I thought you were joking". I was furious, but when I think back to it now, I suppose she was just as shocked and just didn't know what to say at the time.