Denny's just stepped into the 'McWhopper' feud between McDonald's and Burger King

Burger King took out a full-page ad in several national newspapers last week calling for a truce with McDonald's and suggesting that they collaborate to create a "McWhopper" burger.

McDonald's CEO Steve Easterbrook swiftly turned down Burger King's offer and chided the chain for comparing their rivalry to war.

Now the diner chain Denny's wants in on the burger truce.

In a full-page ad in USA Today on Monday, Denny's says it wants to join forces with Burger King to make a joint burger.

Denny's made a video showing what the joint burger - potentially called the "Slopper" - might look like:

Burger King hasn't responded to Denny's offer.