This one, I have a winner. So I lived in an old Chicago apartment back in the mid nineties, I was probably 13 when this happened. Some of my windows wouldn't stay open on their own and needed to be propped. My mom would use wooden spoons and various other kitchen utensils. The spoons would sometimes slide out of place and the window would slam shut. So, in her mind she thought 'use a knife!' The knife blade would be pushed into the sill and wouldn't fall over. Great.
So, one morning, around 6, a thunderstorm woke me up. I remembered the windows were open and I got up to see if the rain was coming in. The kitchen was being rained in and both windows were open, one of them being the nefarious ones that didn't stay open. It was propped with a serrated knife. I did not know this as I was so groggy and frantic from all the rain blowing in. Also there were curtains blocking the knife so I didn't see it. I tried to push the window shut and it wouldn't budge, I realized the knife was there. So, in my 13 year old groggy headed mind, I wasn't thinking. Instead of pushing the window up and lifting the knife out, like Link with the Master Sword!, I just grabbed the handle and pulled toward me. Well, the knife was now thoroughly wedged in the sill and soaking wet from the rain. The knife slipped out of my hand, flipped around in a circle and landed on my wrist. I looked down and saw blood, a lot of blood with a gaping hole in my wrist and some visible white tendons. I ran to my mother's room, the door was shut, and I knocked and tried to wake her up. My mother is an unpleasant woman *especially* in the morning. She is mean in the morning. After telling her I injured myself she told me to put a bandaid on it. I opened the door and stuck my arm through it and told her that no, I really, truly hurt myself. She saw my wrist and freaked out. She made me squeeze my arm like a tourniquet and hold it above my heart so the blood pumped slower. She bandaged it for me and didn't take me to a hospital. Later we went to my grandparent's house and had my grandpa look at it. He grew up on a farm and did all sorts of self doctoring. He had butterfly bandaids [meant for holding wounds closed] and wrapped my wrist in a padded bandage. All I have left is this small, neat little scar. It healed very well and looks like it could have been sutured with how clean the scar is.
Because of the location most people don't believe my story and think it is due to self harm. Luckily I have so many scars now from my job that most assume it's just another animal bite/scratch.