Burger King: advert-body-1 by INGO STHLM

The well-documented burger rivalry between Burger King and McDonald's has heated up once more, with the former teasing the latter about its cooking methods via a series of well-placed billboards (or 'grill-boards').

Burger King prides itself on its flame-grilling; a burger preparation that the fast-food chain loves to tout as its differentiator against competitors.

To highlight its point of difference, Burger King Denmark has placed a billboard next to a McDonald's chain in Copenhagen that directs guests towards McDonald's in case a fire breaks out in its own restaurant across the road.

The provocative sign means to communicate that fires are a bigger hazard in Burger King because, unlike McDonald's, it flame-grill its burgers.

Both Burger King and Ingo Stockholm, who created the campaign, hope well-placed out-of-home creative will stay in situ for a year, marking the brand's longest McDonald's stunt yet.