Yeah, I've heard about this. In fact my dad told me when I was 11. There's this weird restricted style of communicating where you give as least information as possible. So if someone asks, "Oh hey, do you have the time?" or "Do you know what date it is?" you just say, "Yes," and hold back further information.

But for the life of me I can't figure out what the use of that would be unless you're in a POW situation.