WATCH | Burger King pranks McDonald's with 1¢ 'Whopper Detour' offer

The gloves are on. Burger King has launched a devious campaign against its biggest rival, aimed at diverting customers from McDonald's restaurants with the lure of 1¢ Whopper sandwiches. 

The publicity photo is a "Whopper" of a joke. Under a blurred-out photo of the Golden Arches is the bejewelled hand of the Burger King himself, adding the letter "W" in a key place. 

The result: "Billions Swerved." 

Here's how it works: "The Whopper Detour" campaign geofences 14,000 McDonald's locations across the US from the new BK app. 

If a customer steps inside a McDonald's restaurant, the app will unlock a Whopper sandwich for a penny. Once the customer places the order, the user will be directed to their nearest Burger King restaurant for pick-up. The offer is unlocked when a customer is within a 600-foot radius of a McDonald's restaurant. 

Watch the promotional video in which poor McDonald's drive-thru workers have to contend with customers asking for the Whopper sandwich. 

The promotion runs December 4 to 12.