What is the Whopper Sacrifice campaign?

The Whopper Sacrifice campaign was a notable marketing effort by Burger King. It took place during the early days of Facebook, where accumulating friends was a popular trend. The campaign played on this by offering users a free Whopper if they unfriended five people on Facebook. The gimmick, however, included notifying the unfriended individuals that they had been dropped for a Whopper, which was against Facebook's policies. This led to Facebook pulling down the campaign because it violated their terms of service 1.