School cricket pitch, aged twelve so a VERY long time ago...
Previous bat had been caught right on the boundary. The celebrations over, he threw the ball unerringly at the receiving wicket, just as my head intersected the path of the ball. Vaguely remember the impact. Woke up, probably only a few seconds later, and touched the big wobbly lump on my head, which promptly split, leaving a very satisfactory bloodstain on the playing field for some time after. Off to the local A&E, which was not actually very local, and had two stitches in me bonce. I swear there's a dent in my skull...