Many years ago I was working as a bouncer in a biker bar (back when bikers were bikers) when someone behind me grabbed my sweatshirt and yanked it up, presumably going for my .38 snubby I was carrying at 5 o'clock, and I naturally whirled around to deal with whoever was going for my gun.
It turned out it was only one of the waitresses acting flirtatious, planning on tickling me, or something. She had no idea I was carrying, and was kind of spooked I had reacted so violently. It happened so fast she never even saw the gun there. I finally explained it to her a week or two later.