How can your characters exploit coding speech to try to get the advantage? This is something villains would be especiallly keen to use to further their own ambitions. My favourite villains are the smart ones, who show they're brain and not just brawn. The last two Bond films, Skyfall and Sceptre, have kept me engrossed due to this, especially Skyfall. Coded speech is also useful for conveying messages to those "in the know" without being obvious to others. And much can be "gathered" by what is not said, as well as by what is.
Are your characters astute enough to pick up on things like this or do they learn to do so, having had bad experiences of being taken by surprise here? Can your good guys used coded speech to turn the tables on those who've used it against them? If they can, the tension within your story will rocket and that can only be a good thing.