The author gives the example of a time where he was confronted by an angry, drunk stranger. The drunk got right in his face and said, “Do you want to fight?!” There’s no good answer in this situation: either yes or no will get you into a fracas. So the author replied, “The wall outside my house is four feet high.” The drunk said, “What?” and the author said the same thing again, in a very sensible, matter of fact tone of voice. The drunk got confused and as he paused to consider what he missed, the adrenaline rushing through his system and making him combative started to fade.
If you find the concept as interesting as I did, check out some of this guy’s other tips for remembering people’s names, discouraging people from sitting next to you on a subway or bus, and get rid of solicitors.