I let off a firework when I was about 12, it was about 4" long, like a small rocket without a stick, you laid it on the ground, it took off, hit a fence & came back at me, I half raised my arms to fend it off & it went up my jacket sleeve, lodged against my upper arm, still burning, by the time I got my jacket off, a few seconds it had burnt through my flesh, I still have the remains of a scar, over 60 years later,
it was wartime, the treatment then, was to dress the wound with olive oil, but that was unobtainable, so it had to be fish oil, there were no cooking oil in those days, boy, did I stink!