Burger King is trolling the competition by allowing app customers to purchase a Whopper for a penny -- so long as it is ordered from McDonald's.

The fast food chain said the "Whopper Detour" promotion allows customers using the Burger King app to purchase a Whopper for a penny, provided they are ordering from within 600 feet of a McDonald's.

The app will then reroute the customer to the nearest Burger King for their 1-cent Whopper.

McDonald's has not yet commented on the marketing stunt.