In the year 1978, I took a picture of some public officials arguing about the distribution of tax monies, and it pretty much showed the height of the action. But as soon as the camera clicked and the flash went off, the participants realized that their picture was being taken, and things changed. Smiles came out, people leaned back in their chairs, and all wished they were somewhere else.
It was such a noted contrast that I sent the original picture as well as the next picture taken a few seconds later to a national newspaper publication, and they thought it was worth putting in their newsletter. It seems a lot of newspaper photographers around the country had experienced the same phenomenon "when the camera clicked." Click on the image below to see a larger version.