How far will people go to obey authority?
The most powerful example may have come from a real-life con: prank calls that led dozens of managers at fast food joints and grocery stores to interrogate and strip search their own employees.
But the most famous of these occurred in 2004, when a manager at a Kentucky McDonald's received a phone call from a man claiming to be a police officer. He told the manager that one of her employees was accused of theft. He instructed her to strip search the woman, an 18-year-old high school student. The manager did as instructed.
Over the course of three hours, the manager and her fiancé followed instructions from the voice on the telephone. Some of the fiancé's acts were so extreme that they eventually led to his conviction for sexual abuse.
And it was all caught on tape. The above interview includes actual (censored) footage from the McDonald's camera, an interview with the manager, and an introduction with prominent social psychologist Philip Zimbardo. (For those of you in a rush, the intro ends at around 1:30.) The video was created by Zimbardo's non-profit The Heroic Imagination Project, which promotes good choices under challenging circumstances.
The prank calls seem to have stopped after the police arrested a man they accused of making the call to the Kentucky McDonalds. He was later acquitted in that particular case.
Hat tip to Alex Tabarrok, who wrote about this video recently at Marginal Revolution
Further reading: Milgram's electric shock study is one of the most powerful examples of obedience to authority. But it was so unethical that you could never get away with running it today.
A thorough account of the Kentucky case can be found in this story from the Courier-Journal of Louisville, Kentucky.