I rode my tricycle down the basement steps backwards when I was 3. Collarbone, only broken bone I've ever had.
My brother on the other hand, no broken bones, but I think we were taking him to the hospital for stitches at least once a week. I still remember the sound of the thud when we were playing baseball and he caught a ballbat right in the forehead. The funniest one I remember was him coming down the basement steps where Mom and Dad were watching TV. His chin and the front of his shirt completely covered in blood. Mom freaked out and I remember him just standing there saying "What?" Turns out he was playing with Dad's razor pretending to shave. Cut his lip open. Why he didn't realize it with all the blood is beyond me.