According to a study done by biologists at City University of New York, dogs do indeed apologize. Apparently they know full well when they have screwed up and they have a well-developed mechanism to show their regret. We've all seen it, actually -- it's when they hang their heads and put their tail between their legs. In fact it is so easy to spot that there are many hilarious videos on YouTube of dogs embarrassed by being busted. In most of those videos, there are unmistakable facial expressions, as well -- sideways looks and squinty eyes etc.