alt Hacker NewsSo having a signal for switching mediums is something that I feel indicates thinking in the wrong direction.
It's not for everyone. I grew up with code phrases. My mom knew that if I said "I love you" to send in the cavalry. We had similar processes in the military. If I answered the phone a particular way they knew the remote site was under siege.
That's an okay use, but in that use you're not attempting to achieving privacy.
Everyone knows you talk to your parents, but code phrases are not a way to get privacy.