For those who aren't familiar with the technique, two cops (usually when interrogating a suspect) cooperate with one another, in order to achieve a result. However, the cops make it appear that they are at odds with one another.

One acts as the Good Cop, by nicely talking with the suspect, and making it look like he's on the suspect's side, while the Bad Cop acts as if he's ready to wring the suspect's neck. They're working towards the same goal, but the presentation to the suspect appears otherwise.

Well, the U.S. government does the same thing, but it operates on a much larger scale, against 300 million cash cows Americans.