At the end of a longish conversation on WhatsApp, my dad writes "Okay." with that stop.
He means nothing but ok. He's done it so many times. But it breaks the convention of every other WhatsApp chat ending. So I still have to ask myself every time: "I didn't anger him, right?"
When I write 'okay' it's because the spell checker substitutes it for 'ok' & I can't be bothered to argue.
I use 'that stop' to say that I've finished and haven't hit send early or goofed in some other ga-ga Oh Dad! way.
Maybe you're phone & he's laptop and I'm a grammar nerd.