When I was 5-6 years old, I was jumping around on the double bunk bed I shared with my brother. I lost track of where I was, lost my footing, fell off the top bed, and landed with the back of my head smashing up against the edge of the wall.
All I could remember from that point on was a lot of crying, mostly from me, shearing pain, a towel pressed against my head to stop the bleeding, and being rushed to the emergency room to get stitches. When I was in the emergency room, I remember slipping in and out of consciousness with my dad next to me holding my hand. That's actually the very farthest I can remember in all my life. So, that was actually my first memory.
Looking back now, it's possible that if the front of my head hit the edge of the wall instead of the back, or if the doctor poked into something to deep into my head, I could very well be six feet underground right now.