Conflicted fan of McDonald's and Burger King? If Burger King has its way, you may be able to have the best of both worlds on one day, in one location.

On Tuesday, Burger King released an open letter to McDonald's, asking the larger burger chain to participate in a one-off collaboration: the McWhopper. The burger would serve as a ceasefire in the "burger wars" to raise awareness for Peace Day, September 21, a global day of unity supported by anti-war nonprofit Peace One Day.

"All the tastiest bits of your Big Mac and our Whopper, united in one delicious, peace-loving burger," the letter reads. "Developed together, cooked together and available at one location for one day only – Peace Day, September 21, 2015, with all proceeds benefitting Peace One Day."

Related: 10 Fast-Food Restaurants That Now Deliver (If You Live in a Certain Area)

The McWhopper would combine the Big Mac's top bun, all-beef patty, cheese, lettuce, special sauce and middle bun with the Whopper's tomato, onion, ketchup, pickles, flame-grilled patty and bottom bun. The one location at which Burger King proposed it would be sold is in Atlanta, halfway between McDonald's Chicago headquarters, and Burger King's base in Miami.

While cynical customers may have assumed the McWhopper was a mutual play to earn some goodwill for both chains, McDonald's response shows that Burger King's proposal may have been just that: an unexpected and even uncomfortable proposal.

Related: Forget Glitter: The New Thing to Ship Your Enemies Is a Potato

Steve Easterbrook, McDonald's CEO, took to Facebook to post a bit of a frosty response, saying that, while McDonald's appreciated the inspiration to help a good cause, the company would prefer a more meaningful effort to raise awareness worldwide.

"Let's acknowledge that between us there is simply a friendly business competition and certainly not the unequaled circumstances of the real pain and suffering of war," writes Easterbrook. "We’ll be in touch."

The CEO closed with a sassy sendoff: "P.S. A simple phone call will do next time."

While Burger King seems to have its heart in the right place, McDonald's brings up good points in its response. The two multimillion-dollar companies can certainly afford to donate more than the proceeds of one day at one pop-up shop. Additionally, comparing restaurant chains' beef to war seems a bit flippant even if it is based off of Peace One Day's rally cry of "Who will you make peace with?" Most of all, springing a collaboration on a competitor is a bit like proposing to someone on the Jumbotron at a baseball game on your third date – even if your heart is in the right place, it puts the other party in an awkward position.

Related: From Subway's Jared to Bill Cosby: How Do You Make Hiring a Spokesperson Worth the Risk?