I once innocently asked someone I was training
with why his arms were covered in cuts. He muttered
something about "self harm". I was embarrassed, but
it still seems a reasonable question -- given that
it was a martial arts class.
I now have a big gash on my right arm. I would
like to say I obtained this injury from some exciting
activity, but I just scratched it while putting by
backpack on. (It doesn't hurt).