I'm betting you have just learned this by experience! In high school my mate and I were working on models, and he was Dremelling a part...small, holding it to his chest...the Dremel tool slipped off, and going in a circle really wanted to grab something. Grabbed his shirt and instantly twisted it up tight. He started yelling (much like Han Solo to Chewie in Empire) "Turn it off! Turn it off!"
Sadly, despite the danger of dremeling into himself, I was doubled over in hysterics. I did manage to start crawling to unplug it. BUT, my mate tugged and yanked at the power cord, thinking to unplug it. Unfortunately it was in a power strip, taped to a small low table. All he did was knock over the table and then I couldn't breathe the laughter was so intense! He got it unplugged and lived, though his shirt was unhappy.
Hope you have no permanent damage...
