Sometimes you don't even need to be camping, but in the wrong place. Years ago, I was driving through Yellowstone after the season was over. Technically it was at your own risk passage. Stopped at, I think, Yellowstone Lake to visit the facilities. The restrooms were in the middle of the parking lot, so I pulled in front and made a quick turn around the corner into the door. When I was done, I walked out and went to the opposite end back to my truck, but never made it. At the corner of the building was a Bison, his head was about a yard wide and within inches of my head. He snorted and I reversed my tracks and went around the other side.
Seems it was a small herd that ambled up to eat the berries on the bushes around the building. Learned later I was way too close, and could have been squashed against the building. Made it all the way to Cody without any coffee, or having to stop.