What would you do for a free Whopper? Not much, is the most likely answer, but that hasn't stopped Burger King offering free food to people willing to delete their Facebook friends.

The fast-food chain has released an application for the social-networking site that encourages users to remove friends from their Facebook circles in return for a coupon.

Trimming the fat

BK's specially created website explains the drive, saying: "Now is the time to put your fair-weather Web friendships to the test. We'll reward you with a free flame-broiled Whopper when you sacrifice ten of your friends."

As web marketing campaigns go, this has to be one of the smartest, which makes it a shame that it's running only in the US. Still, we're sure most of us could easily lose a few Facebook 'friends' just for the heck of it.