We kept getting calls for someone we did know, but only had sporadic contact. One day, I said that I did know the person but had no idea where they were or when we would hear anything from them. I was then asked if I could give them a message, to which I replied:
"No, I cannot. I am not their personal secretary and I do not take and convey messages. Finding them is your problem, not mine."

Never heard another word.
Also had one concerning the estate of a lady from back home that had recently passed. Just so happened she had married my ex-husband. When I told the person that I had known her, he asked how I had known her. I told him that she had worked for the same company that I did and had married my ex some 10 years prior. After he recovered from the shock, he apologized and hung up. Never heard from him again, either.