Solomon Asch was a social psychologist famous for his experiments in conformity. In 1962 he collaborated with Candid Camera, a TV show, to show just how easy it is to reverse an innocuous social norm: the direction one stands in an elevator.
Does it still work? Watch this University of South Florida replication:
Asch did many such experiments, including showing that people will agree with others when asked a simple question, even if they suspect everyone else is wrong. The implications are obvious. Social pressure is incredibly powerful and we’ll do things that seem pretty bizarre just to fit in. How one stands in an elevator, of course, is a trivial matter and has almost no consequences short of feeling funny. Imagine how much we’ll be willing to do when the consequences are even a little bit greater.