The thread is young but we have a front runner.
AHHHHH!!!
I came in here to write something, but now I can’t do anything except for cringing and reassuring my boys that everything is going to be okay…
As a kid - I was sitting on top of a big oil tank that was in front of our apt building (late 60’s when nobody thought twice about putting a big oil tank in front of an apt building) that my mother had told me a number of times not to sit on, when I saw my mother pull into a parking space. I thought, oops, better get down, and decided that if I just slide backwards off the tank, she won’t see me. So backwards I go, not taking into account that my legs are stretched out in front of me and thus won’t be where I need them to be to land on, so I land on my head, which needed 3 stitches. Not only did she see me, but she gave me a spanking while holding a washcloth on my head for the bleeding.
As an adult - nailing my hand, through the fleshy side part, to the house with a nail gun while putting up window molding. Right as I was pulling the trigger on the gun, which was about 1/2" from my hand that i was using to keep a piece of molding in place, I thought, this is not a good idea.
Tearing apart a mud wrestling ring in bare feet.
That reminds me: I’m due for a DipTet booster.
Fell down the stairs after tripping over a multi-plug extension bar I’d left on a stair tread, and came down on my right big toe, fracturing it in two places, thereby failing to take into consideration Rule Prime of those who live alone: never, ever leave stuff on the stairs.
Unintentionally touched the tip of an ungrounded screwdriver to a live 220 line. Woke up on the other side of the room twitching.
Opened up the right palm of my hand with a paring knife. Somehow I lucked out. The cut ran exactly on one of the existing lines in the palm of the hand. It was a bitch to heal, but today you have to look three times to even see the scar.
Mrs M did the same three months ago (slicing bread, but eh). Mercifully all she took off was some deep skin layers, and the finger has made an excellent recovery.
About forty years ago I was pretending to knife-fight my mirror image, and I was pulling this totally badass move where I hid the point of the knife behind my free hand while I was stabbing, whipping the covering hand out of the way just in time. Or, as the case might be, not. I have the scar to this day. :rolleyes:
I was telling a story and, being an animated person, used my hands quite a bit for effect. While flailing about, my fingernail cut the right side of my nose. Barely a scratch, but it bled more than you’d think.
This happened about two minutes before I was to take the stage for a play in which I was appearing and had to spend the next ten minutes or so delivering lines in a method that was not at all how they were rehearsed.
Man, glad I came in here, as it makes me seem like a genius by comparison.
My best involved using a box cutter to cut speaker holes in cardboard - pulling the blade towards my other hand which was holding down the cardboard. When the blade slipped, I severed a tendon in my legt thumb.
Another time I was assisting a guy present a women’s self defense seminar over lunch. I was the dummy (in more ways than 1!) Was well padded, including boxing headgear. But when he failed to pull an elbow to the top of my head, I remembered boxing headgear does not cover the scalp. Worked the rest of the afternoon one-handed while pinching my scalp together with the next. 8 or so staples.
“Please don’t kick me in the genitals…”
While camping out during the Fourth of July weekend at the Guadalupe River, there was a large, oval, flat rock (about the size of a dining room table) sticking up out of the river bed in midstream right in front of our campsite. Said rock stands about 16"-20" out of water, water is approx. 4’ deep. Pour a 1 pound can of black powder out onto the rock in a large semi-circular ‘line’ (1-1/2" wide x 1/4"-1/2" tall) onto surface of rock. (Imagine the letter C with dimensions of 2-1/2’ x 4’)
Crouched down in the water next to the rock with my head slightly above ‘table top’ level, I ignited the line of powder at one end, with a lit cigarette held out at arms length.
I should note that I had experimented with modern ‘smokeless’ gunpowder, in my younger years, but never with black powder.
I expected the line of powder to ignite and gradually ‘flare up’ along it’s length.
I truly had no idea, that the ‘burn characteristics’ of black powder would be so drastically different from smokeless gunpowder. :smack:
Suffice it to say, when I emerged from the water (after throwing myself backwards to avoid the ensuing fireball) I was minus one eyebrow, eyelashes and all facial hair and arm hair, on the side that was exposed.
Not to mention, the entire side of my body that was exposed suffered a severe first degree burn.
Campers came from 300 yards up and down river, wondering what had caused that ‘huge, flash of light!’. 
And this is not just for men- I saw a female martial artist get kneed while sparring another woman. The whole room full of male students winced in sympathy.
My personal worst sparring injury was a black eye. Failed to keep hands up while monkey rolling, caught a gorgeous twist hit with my eye socket.
“Do it just like that,” I said to my partner, as I bowed out. “Every time. That was perfect.”
What happened to the cake, Biggirl? Were you able to finish it? 
Just so you feel a little better, I was using an immersion blender this past weekend. It got something wound around the shaft so I was digging at it with my fingers inside the blade guard. That’s when I realized I still had my fingers on the “go” button and that it doesn’t take much pressure to activate it!
TL;DR version - I almost did the same thing as you.
Once tried to climb a fence (okay, really a railing) and ended up flat on the concrete on the other side with a cracked coccyx.
The dumb part? It would have taken me approximately fifteen seconds to walk around the damned thing.
Well it’s not going to win any prizes in this thread but years ago when my puppy was small enough to pick up in one arm I was waiting for my daughter to come out of a store so I was running up and down the sidewalk in front of it playing with Mojo. We had stopped our tomfoolery and were walking back to the car when somehow, on a perfectly level sidewalk with no cracks or other impediments to walking I managed to trip, injure both the palm and back of my left hand badly enough to need stitches and chipped my front tooth.
Still a mystery to this day how I managed to fall on both sides of one hand and do no damage at all to the other. I have scars between every knuckle on that hand - all the damage was on the non protruding parts of my hand. Aliens!
Damn, that one’s gonna be hard to beat.
Thankfully, I’m not even gonna come close to challenging JBDivmstr for the title. My tale of self-injury through stupidity is way down the scale from that, even though it made a big difference in my life for several months.
Sunday, January 20, 2013. A dry, sunny, reasonably pleasant winter day in the mid-Atlantic.
The Firebug and I are fooling around in the bed of the stream that goes through the woods behind our house. I’m jumping from one rock to another. I can tell just by looking at the rock that I’m jumping to, that it’s somewhat loose. I know it’s a bad idea to jump on a loose rock. I do it anyway.
Next thing I know, I’m face-down in the stream bed, half in and half out of the water. I think I’ve just slipped, but am OK, other than being wet. I test my right foot before putting weight on it…quite fortunately, because it immediately lets me know that it would be a bad idea if I tried to make it bear weight. It doesn’t hurt, really, but I bet that would have changed fast if I’d tried to stand on that foot.
Fortunately, we’re only about 200 yards from the house, so I crawl back on my hands and knees, laughing and shaking my head at my own stupidity and the ridiculousness of the situation the whole time. My wife takes me to the ER, where I find I’ve completely ruptured my Achilles tendon.
It’s pretty much back to normal now, but it took surgery, physical therapy, and months of recovery time to make that happen.
I was about 17, climbing into bed with the lights out. Bed was next to an old steel desk, desk had the extender out, on which was a pencil with crimped metal where the eraser used to be.
Next morning, Mom was fussing at me about getting blood on the sheets. I didn’t even know I had been bleeding! Sure, I had felt pain in my leg when I was getting in bed but didn’t think anything of it.
Almost cut off a fingertip while playing with a hatchet. It’s been like 30 years and I still have very little sensation in that area.
I’ll see your sneeze, and raise you a “getting up off the toilet” for throwing out my back.
I remembered another.
At about 6 years old I knew how irons worked.
However I looked straight at that iron and thought “I wonder if it’s still hot.”
“Well I can only tell by touching it right?” I incorrectly thought.
I put my finger right on that sucker and it was blazing hot. I didn’t tap it, I just stuck my finger right on there.
About 2 seconds later before the bawling kicked in, my mother yelled from the kitchen, “Don’t touch that iron, it’s hot!”
(mostly it’s a tale I tell for the punchline inadvertently created by my mother, and this thread gave me the opportunity)
Ooh - just remembered another martial arts-related one.
Bought a heavy bag and hung it in the garage. Was “showing off” for my young (maybe 8 yrs old) son, doing stupid “flashy” kicks I NEVER did in the arts I practiced. As I focused on what I considered practical fighting/self defense, I NEVER kicked above waist level, and NEVER did spin moves. So of course I was showing my kid my mad spinning sidekick skills.
Delivered a right kick, then spun to give a left kick. Misjudged the swing of the bag, and heard a loud CRACK! THAT definitely got the kid’s attention, and he gleefully said, “Do THAT again, daddy.” I mumbled “Maybe another day” and limped inside. Whereupon I encountered my wife who was leaving for the evening, and said in passing, “Will you vacuum while I’m gone?” So, hoping it is a sprain that I can hide, I CRAWLED through the house with the vacuum. Middle of the night it stared throbbing the way (IME) only a break aches.
Perhaps the stupidest thing I did was wake my wife to tell her I thought my ankle was broken. My loving helpmate’s supportive and sensitive response? “What did you wake me for, you idiot? It will still be broken in the morning!”
Yeah, it was shattered right above the foot. That’s now the one (of many) old fractures that is best at predicting changes in the weather! 