ArfinGreebly's post reminds me of my wife and me. We don't have pre-defined phrases that we use, but we do speak indirectly about things like Arfin described. Context is a huge part of it, and we are generally very nonliteral in our conversations. We do talk to each other A LOT, including about defensive scenarios, so we have a strong base of understanding to begin with when something of interest comes up.
We do have a lot of "inside references" to things for when we need to be more direct, yet still discrete. One of us might quote a line from a movie, for example, that rerfers to something at hand. Like "Probably some local fisherman, out for a pleasure cruise, at night... in... eel-infested waters" might mean that someone appears to be following us.