I've had that happen before! Wakes you up real quick!
When I was younger, I was building a log house. In order to do so, I would straddle the walls above the doors and windows and drill 3/4" holes in order to set 2' pieces of rebar to lock the top log across the openings. We used a 1 hp "hole hog" drill that had TONS or torque. When you let off the trigger, it would take about 20 seconds for the drill to fully wind down.
The drill bit we used was a self tapping Auger bit.
One time....... And ONLY one time, I pulled the drill out and set it on my lap. In doing so, The self taping tip grabbed a hold of my jeans. My hand was off the trigger but just the power of winding down quickly wrapped up my jeans in a very similar knot as the photo above. It created a turnikate beyond believe!
I ruined a pair of jeans, and had a beautifully colored bruise about 3" wide all the way around my thigh.
It was a tough lesson to learn.
Remember safety. Sometimes a hard lesson learned is a lesson that cant be learned again.....after loosing a limb or an eye.