If they're good then they can stay (for a while).
One bloke took my ciggy and got me to burn a hole in my mate's suit jacket (we were at the Crimbo bunfight and all dressed to the 9's).
I did it. I burnt a big hole in his expensive jacket. Saw it with my own eyes.
I stood back, the magician shook the jacket....and there wasn't a mark on it
I had spies at every angle and no one could work it out.
Being rat faced didn't help I don't suppose.