›You might say you have to see a man about a dog when you do not want to say what you are really doing, especially when going to the toilet: I've just got to see a man about a dog. I'll be back in a minute.
According to sociologists (=people who study the relationships between people living in groups), we are good at lying. As a species, we have developed a remarkable ability to deceive each other (= persuade each other that something false is true). Being able to say things that are not true can help with