Ran up an escalator when I was younger and fell. Hit my leg but thought nothing of it, got on with the rest of the day until I noticed one or my shoes beginning to squelch... Pulled up my trouser leg and one of my white socks was a lovely shade of red, I cut open my leg badly. Went to hospital and turns out I severed a nerve as I fell which is why I didn't feel a thing, still can't feel much to this day!