Just about every single plastic container that I own has a "C" written on it. For some reason Angie wanted to be certain that my containers did not get mixed up with anyone else's containers. As far as I know there was never anyone else bringing her left-overs in plastic containers, but she persisted in making the "C" no matter what I said about not needing to.
Once when we went to eat at my brother-in-law's house, my sister-in-law packed up a nice plate of leftovers for Angie. I dropped it off at her house on the way home. The next morning I called to tell her the container was not mine so don't put a "C" on it. Mom said "oh, ok". When I picked up the containers later, sure enough, there was a "C" on it, but she had done her best to cover it up ... with white-out.
I can't make this stuff up.