Burger King just launched their Halloween Whopper, which is a normal whopper that’s decked out with a pitch-black bun. But there’s reportedly a catch post-consumption when bowel movements start to occur: bright green poop. Yes that’s right, the Halloween whopper changes people’s stool to a disturbing shade of bright green. 

It’s not clear as to what ingredients might cause color change, but a rep from the company told ABC news that the bun is made with less than 1 percent food dye. The rep also indicated that the pitch-black color is from the, “smoky black pepper flavor of A1 baked into the bun.”

Some burger-eaters reported having bright-green poop for up to three days.

Certain foods and foods containing specific dyes like Green #3 or Red #40 can not only alter the color of your bodily wastes but also produce unpleasant smells. Click on through to find out what’s causing that funny odor or color. 

Beets 

This muscle pump-enhancing food can leave a surprise post-consumption, turning your urine pink or red. It can be alarming at first because the color can be mistaken as blood. Beets can only maintain their pigment color at certain points of stomach acidity — making it too faint to appear in some people’s urine. Having pink or red urine is termed “beeturia” and is only seen to effect 10-14 percent of the population. 

Asparagus

The greener the better for when it comes to the nutrition profile of asparagus. However, 15 minutes post-consumption the green vegetable can pack a pungent urine smell. The reason is that asparagus has a rich sulfur-containing compound called asparagusic acid. When our digestive system breaks down the compound, a volatile odor gets released. Interestingly enough, not all asparagus eaters are plagued by the foul smell. Two theories have been developed by scientists saying that some people have the digestive properties to metabolize asparagus’ sulfuric compounds to release the odor or that everyone produces the nasty odor, but only some people can smell it. Several studies have been done, but the numbers aren’t consistent to give a direct answer. 

Beans

Like the saying goes, “Beans, beans they’re good for your heart. The more you eat, the more you fart.” Beans can be a muscle-building staple, but they can also create some awkward circumstances in public. Beans create gassy bowel movements because they contain the sugar molecule, oligosaccharides. Our body doesn’t produce the enzyme to metabolize this sugar molecule, so bacteria in the large intestine break it down. The end result: gas. 

Red #40

As mentioned before, dyes can cause a color change of the stool. Red #40 is a common food dye and can easily be found in Froot Loops, Jell-O, red candy, and so on. Over consumption of a food that’s infused with Red #40 can lead to red-colored poop. 

Beta-Carotene Rich Foods

Fall means a lot of pumpkin and pumpkin contains a hell of a lot of beta-carotene. Beta-carotene has the potential to make your poop have an orange tint. Other foods that are rich in beta-carotene are carrots, oranges, and sweet potatoes. 

Curry

There are certain spices that can maintain their pungency after going through the digestive system. Foods, like Indian cuisines, that are highly flavored in curry can cause your urine to smell a bit spicy. The reason: the ingredients move past the odor-triggering chemicals via the kidneys. 

Garlic

It’s loaded with health benefits, but can also cause your urine to have a strong odor after a heavy garlic-flavored meal. That’s if the garlic is raw, because cooking garlic can help reduce the amount of methyl-mercaptan that’s passed through the kidneys.