I believe that online campaign with simple execution and prizes will always work, much more better than those involve complicated mechanism. Your audience simply does not want to read a full page long instruction so do not try to confuse them.
Early of this month, Burger King launched a campaign called Whopper Sacrifice. The campaign utilized the popular Facebook Apps platform to hit their viral objective. What you need to do is, add the application and remove 10 friends from your Facebook network through the application in exchange for free Whopper coupon.
“You love your friends, but you love the Whopper”
The friend removal is what the “sacrifice” they mean for. When you remove your friends, a notification will be sent to them, telling them they have been “sacrificed” for a Whopper. The campaign was so impactful that attracted ten of thoudsands Facebook users a day.
Unfortunately, Facebook was “unhappy” with the promotion campaign as they have violated the Facebook user policy. Under normal circumstances, no notification should be sent when you remove a friend. However the Whopper Sacrifice application posted the news feed to let others know about they have been “sacrificed”.
The application had last for one week plus before being shut down by Facebook. 233,000+ friends had been removed and 80,000+ users added the application.
The campaign ended in hilarious way but still it is fun to be a case study.