10/05/2015 10:09 EDT | Updated 10/05/2015 10:59 EDT

Burger King's Halloween Whopper Turned People's Poop Green, Customers Say

This is one thing that comes out greener on the other side.

Burger King's black-bunned Whopper comes out greener on the other side, reports say.

Numerous social media users say the fast food chain's Halloween Whopper is making their fecal matter turn green for as long as three days after they eat it.

The bun is made using A.1. Sauce, which is often used in meat dishes and others. And the company says it's this precise ingredient that gives the bun its scary colour.

But many report the burger isn't the only thing that has a different look:

Maxim writer Chris Wilson said his fecal matter was a "ghoulish shade of green" after he ingested the burger.

"Sadly, this festive poo only appears within a day of ingesting the Halloween Whopper, so there's no hope of saving up for St. Patrick's Day," he wrote.

The New York Daily News said that food dyes such as Green #3 have been said to turn excrement that very colour.

But it also quoted a Burger King spokesperson telling ABC News that the Halloween Whopper's food dye content is less than one per cent. The newspaper also noted that the chain doesn't say which dye is used in the burger.

The shape, size and colour of your excrement can mean lots of different things.

When it takes the shape of a pebble, for example, that's a sign of constipation, gastroenterologist Dr. Laurie Deleve told BuzzFeed earlier this year.

And green, she said is a "perfect poop." Meanwhile, the Mayo Clinic identifies food colouring as a possible cause, though it adds, "only rarely does stool colour indicated a potentially serious intestinal condition."

In the meantime, here are more social media users who reported a change in the colour of their poop:

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