I had been spreading grit and salt with my hand (to keep my glove clean) and thought I would clean it and the bucket with snow. Big mistake.
Picked up a load of clean snow with the same hand. The pain was almost instant, and excruciating. By the time I had got to some clean water to wash it off, I genuinely thought I had damaged by fingers, although the pain was only in my hand, as all the fingers were now completely numb. I could see the skin was not in a good state, and guess that is what frostbite is.
Anyway, although I could feel it for a few days, there seem to have been no longer-term permanent damage.
But bathing my hand in salt solution that might get as low as -17C was clearly rather a Silly Thing.