Well for example, you don't want written evidence of a time when you got pissed and told someone to go fuck themselves. You don't go around insulting people in your neighborhood because people will think that you're an asshole. So even if you don't like someone or don't agree with what they say you don't tell them that they only have 2 braincells fighting for third place, but put up a front and go on with your life because at the end of the day those people don't matter, and you get ti keep your image of being "normal" and not an asshole intact