Before I give a talk I often start by greeting the audience and by asking them a question that at first seems common enough:
How are you? Comfortable? The obvious answer for most people is in the affirmative. However, my response is what tends to surprise them, which is the reason I use it.
Well, hopefully we can change that. It catches them off-guard and gets their attention, which is one of the reasons I use it. But even more importantly, I say it because I really want them to be uncomfortable.