In many common social situations, etiquette or expedience often requires you to smile warmly at someone whose violent death you are at that very moment imagining. The goal is to be rid of the dolt/asshole/lunatic, to bolt without seeming to bolt, so that the d/a/l won't pursue. Just think of the social calculations that can run through your head as you plan your escape, the angles, moves and possible countermoves figured, all the permutations considered, all done in the background while you maintain a veneer of casual chatter so as not to give the game away. It's really a marvel of computational firepower. Those computers that play chess with Garry Kasparov would begin emitting sparks and screeching "ER-ROR!" if confronted with the task of nimbly extricating themselves from a conversation with an offensive blowhard or borderline sociopath at a party.