Burger King "Whopper Sacrifice"

What would you do for a free Whopper? Now is the time to put your fair-weather web friendships to the test. Install Whopper Sacrifice on your Facebook profile, and we'll reward you with a free flame-broiled Whopper when you sacrifice 10 of your friends.

Check the site here:
Whopper Sacrifice

Agency: Crispin Porter + Bogusky, USA.