I've heard him say it a few times and always assumed it meant keeping your chin down but I was never sure.
I also love when he says, "work behind that stick and swim without getting wet"!
Tip your hat, in the context he used it for the Dawson fight, meant say hello. Open up a bit and see what his gameplan is when you do. This way they see what Chad's up to and how they can use that knowledge.
That's my take on it anyway.