Always wear your safety glasses when mowing the lawn or weed-eating. I didn't today (though I do half the time), and I got hit in the eye with a rock that was launched by the mower blade, bounced off the side of the house, and hit me in the left eye.
My first thought after I let go of the mower — which killed the engine — and put my hands to my face was, "Is the eye still in the socket? Yes. Can I see out of the eye? Yes!"
It hurt but might have scared me more than anything else. Of course, the eye is blood-red now — and wanting to close as I type this — but I think I'll be okay.