My pack of hound dogs know what a jingle of the car keys means....you better get out of the way or they will stampede you on the rush to the truck.
The dogs of a friend of mine quickly learned what “a walk” was and would go insane with excitement whenever they heard that word. To alleviate the insanity, my friend began using the code “W” to indicate a walk. Sure enough, those dogs learned what a “W” was and drove my friends crazy until they came up with yet another code word: “Two U’s” That was the last I heard of it, but I’ll bet those dogs broke that code as well.