What was your most painful injury?
Not the most interesting topic, but seems poll-worthy to me.
I get hurt relatively often, but it usually isn't all that bad. I remember it being horribly painful to have a needle (for a numbing shot because I needed stitches) jammed into a portion of my heel that was already cut open, though. I had lost a piece of my heel when I stepped on a glass picture frame. Still can't feel part of my foot because of that, but the nerves seem to be slowly healing. I really need to go dig up the picture of my stitched-up foot to post here ahaha.
If not that, then I'm going to go with twisting my ankle sometime ago. Seems lame, but by how painful it was, there was potential it had twisted far enough to break. I was amazed that it was possible for something to hurt that much without easing. I was with other people, so I just had to fake a straight face and limp back to the car (I couldn't put any weight on that foot/ankle).
It was also painful having my sister drop me on my head on the corner of a glass-top stove when I was like 7. My best friend pointed out that it could have been worse: the stove could have been turned on.
Having my face covered in severe second degree burns wasn't very fun, either.
Those are the only ones I can remember. I'm sure literally having my skin burned off with chemicals must have hurt like heck, but I can't remember it.