I shall now use the phrase "verbal canary" as often as possible.

I've been reading the "Stuff Christians Like" blog since the author, Jon Acuff, started posting a few months back. I've avoided linking to it since the signal-to-noise ratio is a little high - he writes five or six posts a day, four of which can easily be skipped over, plus updating two other blogs at the same time. But today's post - #291, "Saying 'I Was Just Flipping Channels' When You Watch Something You Shouldn't," had a great bit:

Lean in close and I'll tell you a little secret. Sometimes, I used to throw out ideas just to see how you'd react. I would say something like, "Yeah, this guy I know went to that new night club and said it was crazy." Then, I would pause and get your reaction. If you responded by saying, "I hate night clubs and so does God," I would agree and say something like, "Amen, God wants to smite them. Probably use sulfur, if I had to guess." But if you said something like, "Let's go check it out," I would say, "Yeah, that sounds fun." It's kind of like how coal mines used to have a canary down in the shaft with them. If the bird died, something was wrong with the air quality. Well what I do is introduce a verbal canary. Then, if you kill it, I can still look holy and say something like, "yeah that bird sucked anyway."
Here's the link if you want to take a look around. Personally, I recommend checking out these first: