I was driving along the freeway one day, coming up on a truck in the next lane at about 100 km/h. A sheet of Gyprock (about 2.4m by 1.2m) that was lying unseen on the road in my lane got flipped up by the truck as it passed. I didn't know what it was - all I knew was that a seemingly solid wall had just materialised 10m in front of me. Funny how time slows down. Anyway, I hit the sheet and it shattered into a million bits, leaving me unscathed and in need of a nappy.