In my profile, I used the picture of my wife, Sue, and me posing for a picture (there was a band of gorillas 'safely' behind us) because it's pretty unique.
The picture was taken in Rwanda at one of the gorilla reserves. Before setting out, we were given repeated warnings about how to act around the gorillas and specifically not to get within 30 feet of them.
My wife and I had no idea that this silverback male was walking behind us on his way to eat some bamboo. Afterward, when we were shown the picture, we asked why no one alerted us to the potential danger.
The guide said that he was afraid that if he warned us that we had a gorilla walking that closely to us, we might have jumped away exciting the silverback who might have mauled us. Since we were posing and still, letting us be seemed the best idea....which it was.