Took like three days for my poop to stop being green, but was totally worth it, @BurgerKing — Toasty (@ImHunterStanton) October 5, 2015

@BurgerKing STILL HAVING #GREENPOOP FROM YOUR #HALLOWEENWHOPPER YOU NEED TO RESPOND TO THIS BECAUSE ITS REALLY MESSED UP — Dr. Pluto A. Planet (@PLUTOAPLANET) October 1, 2015

At the #HalloweenWhopper just to see what the black bun is all about. It was good, but one side effect, #greenPoop the next day — Jessica (@jessz2cute4u) October 2, 2015

The bun on Burger King's new Halloween Whopper might be black, but it'll have you seeing green on the other side of that experience.Reports have surfaced that the black burger bun, which was a hit with Japanese consumers last year, will stir your stomach to create a green bowel movement, with shades ranging from neon to hunter green.Call it curiosity-an abc13 staffer decided to try it."I noticed flecks of green in the bun itself," our colleague said. "I wondered if it was mold but for the sake of science, couldn't stop myself."The end result: "Yep, it came out Frankenstein green."Meteorologist Don Schwenneker at our sister station WTVD-TV also said the Halloween burger left him feeling "haunted.""I ate this one and for two days was haunted by the color green," Schwenneker said on his Facebook page We're not the only ones to notice. On social media, the hashtag #greenpoop is starting to trend with people sharing their own encounters of the green kind:Burger King tells ABC News the dark bun's color comes from the "smoky black pepper flavor of A.1. baked into the bun," and that it contains less than one percent food dye. The concentration of food dye in the bun meets Acceptable Daily Intake measurements approved by the Food and Drug Administration, the company says.We reached out to Burger King for comment about the green poop claims, but we have not heard back from the company. We'll update this story as it unfolds.