I busted my left knee when I was in the army (it was in March 4, 2001).
While that sounds hardcore it is not, it wasn't in any combat or usually dangerous situation...
We (me and three other soldiers, 2 on each side) were lifting the front side of the truck trailer up so it could be connected to the truck, when the two guys on the other side decided for shit and giggles to drop the trailer on their side, me and the other guy had to try and keep it up for a few seconds so we could jump back (we couldn't hold the damn thing by ourselves for long, it was fully loaded and weighted like hell) to avoid the thing to fall on our legs/feet, I yelled to my mate to jump back while I kept trying to hold it off, he did so... I unfortunately overestimated how strong I was and as soon as he stop holding the trailer it juts came crashing on me, I jumped back but wasn't fast enough and so there goes a kneecap... Still hurts like hell when it rains and I can't or shouldn't run for more than a few steps.
The worst thing about that was that the trailer was full of tents and other materials to mount a camp to assist emergency crews, because a bridge had collapsed and a bus and three cars had fallen into the river and 59 people died, and those assholes decided to pull a prank like that which delayed the whole fuckin operation and costing an assigned man that had to be replaced (me) which took a few more minutes.
And when I was a kid (I don't remember this to be honest, but I can feel it in my skull) around 4 years old, I got my head kinda "crushed" by a pile of bricks that I so intelligently decided to climb... And when I did, all the bricks fell on me like a jenga tower.
I only know about it because later when I was older I asked my parents why I could feel small hard bits under the flesh below my left eye socket. And they told me it was from the same thing that allows me to feel a strange "dent or crack" from the top of my head coming down the center of my forehead and ending in the top of my left eye socket, and that those hard bits are bone fragments that back then the doctors decided it wouldn't be dangerous and would be worst if they operated to remove them.
Those are the two worst ones for me.