“My credit card number is 1234 or 4321!”

I worked at a call center for a catalog company where our customers were primarily elderly people. One day I was placing an order for an older gentleman. I had taken down all of his information and entered his items, so next I needed his credit card number. He told me that he couldn’t remember the number for sure, but that it was either 1234 or 4321. (I don’t remember the actual numbers he gave me, but he was sure that it was one of 2 combinations of 4 numbers.) I tried asking for the entire credit card number, but he kept insisting that it was “either 1234 or 4321.” I tried explaining that credit card numbers consist of 16 digits, but no, his credit card number was “either 1234 or 4321.” This went on for awhile, with me losing my patience and him angrily repeating that he was sure his card number was either 1234 or 4321 and could I just try them both. No sir, I can not try them both because what you are giving me is not a credit card number. He eventually hung up because I was apparently too incompetent to place the order for him.