X-ing a sandwich

Our friend Alex was coming over to practice guitar with Mr. M. So Mr. M and I decided to go out for sandwiches before he came over. Unbeknownst to me, the plan was to buy a sandwich for Alex. Mr. M and I ate our sandwiches, and put all the leftover trash in a bag after we were done. He handed me a bag, with instructions to "take care of this." Keep in mind that I didn't know we had ordered a sandwich for Alex. I thought he had handed me the bag of trash. So to anyone (including me) who's ever seen a mafia movie, "to take care of someone" means to rub them out, X them, turn them into fish food, nix them-basically to kill or get rid of them. So how could Mr. M not realize that I was doing just what he asked me to when I threw away Alex's sandwich?