Many years ago when we were building a cold bin to store vegetables over the winter, my younger brother who was about four at the time decided to try and slide down the blade of a freshly sharpened buck saw, slicing his knee badly enough to require stitches.
Years later I was trying to dam up a swampy area to make a small pond, and felling a couple of trees to form the top of the dam. One of the trees hung or lodged in the brances of a nearby tree. Remembering movies of South Sea natives using machetes to cut foot notches in palm trees to enable them to climb to the top and get fruit or nuts, I began cutting notches in the trunk of the tree with an axe, intending to cut it free where it was lodged, and thouroughly forgetting that newly freed end of the tree, with me on it, would fall much faster than I would had I only jumped off the opposing tree. As good (?) luck would have I only managed to cut three notches before the axe rebounded from the tree and struck me in the knee, requiring a week or so in the hospital trying to stop the various infections I had contracted from the swamp water.