When I played OTB in a former life, some rather snobbish young geniuses in our club played a3 or h3 in such situations - ie they were ahead by a Queen or so, their opponent refused to give up. a3 was a move that you'd expect from a losing party - not bad, just utterly pointless.
They were prepared to go on and win, but in many cases, such a move made the losing player realize he was making a fool of himself, contemplate the futility of all human endeavors and the brevity of life, and resign sooner. Less effort needed than for a 5-Q mate (but well, if you are up for it, it's not cruel at all, I think - just stay indoors, remember that lightning bolt).
Yeah, I know...this has been discussed before.
Here's the deal. We are in endgame. Material: me 16; he 2.
He won't resign. Many of his other games have been won on time. I suspect that he hopes God will deal me a lightening bolt, a heart attack...something where I will either walk away from the game or be carried away.
I don't chat when I play. After move 39, I did for the first time. I said: "Looks like you are hankering for a 5 Q mate."
This is what I am going to do. Is this cruel of me?