Burger King, through their insanely creative advertising agency Crispin Porter + Bogusky (see their recent Burger King perfume launch), launches a Facebook application that encourages users to remove Facebook friends. Sacrifice ten of them and you got a free Whopper. 233,906 friends were removed by 82,771 people in less than a week. Facebook is overjoyed, right? What a great example to show the Madison Avenue agencies on how a big brand can get real engagement from users. This is the future of advertising. Or it could have been, if Facebook hadn't shut it down, citing privacy issues.