This year, Burger King introduced a special Halloween Whopper with a black bun. The black bun Whopper has been available for years in Japan, but this is the first year it was made available in the U.S.

Maybe they should've left it in Asia.

Apparently some people are finding there's a weird side effect of the black bun on the Halloween Whopper - it's turning their poop green.

Once again, the Internet proves its worth as people have been taking to Twitter to discuss their unnatural bowel movements, and even sharing photos of their Incredible-Hulk-style green poop. We accidentally looked at one and would strongly recommend you don't.

The ingredients for the bun include A1 steak sauce and four different food colorings (as opposed to the squid ink used in Japan), so somehow those ingredients are teaming up to have this colorful side effect for some people.

Fortunately, there's almost no chance the green poop is a sign of any real health problems. Once the bun is out of your system you'll be back to nice traditional brown feces again.