When I was much, much younger I waited tables at Kips Big Boy. Some guy came in and ordered a spaghetti plate (at a hamburger joint?). He had, or pretended to have an Italian accent. I served him and a couple of minutes later he called me over declaring "This is not spaghetti!!) and threw the contents of the plate on me. I went and got the manager and let him handle it.
My point in posting this boring story is...it never crossed my mind to shoot the jerk!!* Times have changed so much that this seems to be an acceptable solution.
*I was only about 17 at the time. If I were working in that industry today, much older me, my response would probably be more...forceful.

Which is why I realize I no longer have the temperament.(or the physical stamina)