I cannot begin to tell you how many smoke drills I have conducted in the simulator. Despite a thorough briefing, a lot of people would keep forgetting to switch off their mike when not actually talking and give us all the benefit of their particular version of heavy breathing.
I could always tell when I had ex-military pilots in the front. They were much more disciplined simply because they had come from a background where as many as five crew members would be wearing oxygen masks and they had learned that without discipline, chaos would quickly ensue.