You’re probably already wondering, what the heck is a “ghost poop” and what does it even mean if you have one? In a recent video, YouTuber, gastroenterologist, and Men’s Health columnist Dr. Sameer Islam, shares what this elusive poop says about your toilet habits.

Dr. Islam gives us three definitions of the elusive ghost poop: 1) the urge to poop that ends up only being gas, 2) a poop so smooth that it went down the drain before you could see it, and lastly 3) a visible poop in the toilet, but zero poop marks on your toilet paper after wiping.

As far as the first type of ghost poop, “This is caused by having too much air in the colon and in the rectum as well,” he says. “It innervates or activates the nerves inside your colon [and rectum] and gives you that urge to have a bowel habit.” The culprit? Eating gassy foods, being constipated, or even swallowing too much air.

The main way to prevent this ghastly gas is simply to avoid eating foods that give you lots of gas, avoid swallowing too much air (typically by drinking straws), and keeping your bowel movements regular, he suggests.

The second ghost poop isn’t one to worry about, Dr. Islam says. It should actually be celebrated for being such an amazing bowel movement.

The third type of ghost poop might feel bizarre, but it’s also nothing to fear, according to Dr. Islam. “It’s like a ghost that leaves no trace,” he says. This is a sign you had a poop so small or so smooth that simply didn’t leave a mark—zero cause for alarm.

Dr. Islam’s tips for your best poop yet, with or without ghost poops? Eat more probiotic and magnesium foods like kimchi and whole grains, spend less time on the toilet, and consider in a bidet and Squatty Potty for cleaner, more efficient bowel movements.

Taylyn Washington-Harmon is a writer and editor based in Chicago. Her work has appeared in Men’s Health, Health Magazine, and SELF.com. You can follow her on Twitter and Instagram at @taylynharmon.