(CNN) - Burger King is trolling its biggest rival with a promotion available through its mobile app.
For a limited time, you can order a Whopper for a penny but you can only do it at McDonald's.
All you have to do is get within about 600 feet of a McDonald's and use Burger King's BK App to order a Whopper.
Then, just drive to the nearest Burger King and pick up your sandwich at the cost of a penny.
The promotion called the “Whopper Detour,” runs through Dec. 12.
Burger King launched the promotion with a video showing people trying to pick up their Whoppers at McDonald's drive-through windows.