A jargon-coded message changes words instead of replacing individual letters. Jargon code is word-crafting at its finest and usually requires a good bit of imagination on the part of the sender. A good number of years ago I worked summers at Disneyland as one of the boat drivers on the Jungle Cruise. After being there for a couple of weeks I was introduced to the local jargon code, which the male employees used when an attractive woman was within eyeshot. The word was "Alp" and it was surprisingly effective for those of us who knew what to listen for. This one word allowed a few guys to effectively communicate in crowds of several hundred people at a time without drawing undue attention. I realize this example could be the simplest form of jargon code; normally, it is more than just one word, but it illustrates the point of communicating out in the open quite well without anyone noticing.