We have done the Spot thing before. My grandfather called my sister Spot when we were kids just so that he could say that when we were heading out to the car.
When I think about it, right now we're doing "Clean up on aisle 5" for "Eat what just fell on the floor". "Yeah, I don't think so" has replaced "Drop it", "Leave it" and anything along those lines. "Be nice" means "Leave your older sibling alone". There's probably a lot more. As time goes on, we have become increasingly conversational. They know what we're talking about.