MIAMI -- You don't have to go to Japan to try Burger King's black-bunned Whopper.
Burger King is bringing it to the U.S. just in time for Halloween.
"Something wicked is coming," the burger chain on Twitter, with a brief promo video featuring thunder and lightning and a lunar eclipse, with a burger standing in for the moon.
But it's not just the color, insists Burger King. It's also the flavor, with A.1. sauce baked into the bun. According to Burger King, it's the sauce that turns the buns black.
— Burger King (@BurgerKing) October 5, 2015
"While the pitch-black bun gives the Halloween Whopper sandwich a look that may make some think 'hmmmmm?' the burger's classic A.1. flavors will have tasters saying 'mmmmm,'" Burger King said.
Burger King has been selling colored Whoppers in Japan. As part of a summertime promotion, the chain sold "samurai burgers" with red or black buns.
In the U.S., the black Whopper has 710 calories, 43 grams of fat and 1.5 grams of trans fat. That makes the nonblack Whopper look relatively slim, with its 650 calories, 37 grams of fat and 1.5 grams of trans fat.
The black-bunned Whopper is only the latest of a series of experiments that Burger King is conducting. It recently launched a "burger merger" with several other burger chains, including Wendy's, to create hybrids of their rival burgers.
While the Whopper looks appetizing, it appears to have some unpleasant residual effects in the toilet. People have been taking to Twitter to say the black bun is turning their poop green.
— Moo (@Mooslan) October 6, 2015
— Eddie Mitchell (@FDNYMECH) October 6, 2015
— 💛Booty💛 (@BootyHaver) October 6, 2015
The hashtag #greenpoop started to trend, and some people say they want to try the sandwich to see if it really happens. Others are upset at Burger King and want an explanation about the black dye's health side effects.