Who said there was no free lunch?  Burger King continues to innovate with strong social applications. Following Subservient Chicken, AngryGram and Whopper Virgins, the folks at Crispin Porter + Bogusky came up with a great application called Whopper Sacrifice. 

The concept is brilliant: BK rewards users with a free Whopper (via coupon) for every 10 friends they REMOVE from their Facebook friends list.  The brand message is about preferring the whopper to the excommunicated friend.

Why is this a brilliant campaign?
1. The viral communication is driven by a social ACTION with social consequences.  The ability for a brand to harness and encourage social behavior to drive its own associated brand message is huge. and BK is doing a really god job here with a cool brand statement to boot.

2. Its true that we all have a lot of Facebook friends we can get rid of.  But try it.  Its not that easy to communicate to 10 of them that you no longer wish to be their friend. One has to invest not only the time to find the 10 friends they can banish, but invest real social currency: risking offending the recipient.

3. Rewards: The Whopper is a tangible and valuable reward for the participating users.  Great incentive that is 100% on brand.

4. Its gutsy and simple.  And Gutsy and simple always promises to gain street cred.

And I love the visual.  You are literally sacrificing your friends, seeing them burn, one by one to get to your burger. 
Install it here: http://www.WhopperSacrifice.com Its Awesome!