If I where to own a store that had a no-smoking policy, and someone smoked inside, would it be legal to spray them with a fire extinguisher?
I had that material sewn onto my vest while refueling Helicopters in the service and after retiring, I had a traffic vest with it on as well. Never got hit!
If it's black then adding safety pins may look more gothic or punk. Maybe you could create a slit and tie the ends together to make it tighter at the waist. If you want to use a safety pin then pin it from the inside so it doesn't show.
