Down the internet rabbit hole of inedible “forbidden” food.

The slice of New York–style cheese pizza looks perfect. Pulled straight from the oven and freshly sliced, it still has gooey mozzarella tendrils along its edges. The lava-like red sauce erupts from the dough, and the cheese sweat glistens on the surface. You want to fold the floppy triangle over and take a big bite, the roof of your mouth be damned. And then you click on the thumbnail image for a higher-resolution look, and it’s revealed that what you thought was pizza is actually a filthy rag turned reddish-brown from wiping down a rusty metal sheet. Even knowing that, one man can’t help but write: “Damn this made my mouth water, that mozzarella is looking hella good.”

Welcome to the world of Forbidden Snacks, an internet meme started in late 2017 that has just begun to enter the mainstream over the last few months. The slang term refers to objects that appear as though they may be edible and delicious but are actually anything but.

A tub of blueberries that are really miniature sea turtles. A burrito that’s a dinosaur bone. Brownies that are bronzer. Fresh-squeezed OJ that’s an acrylics rinse cup. The entire idea was initially created as a spoof in response to #teens that were challenging each other to eat the candy-looking but highly toxic Tide Pods during the winter of 2017.

On November 1, 2017, a Tumblr user jokingly posted a photo of colorful bath bombs, multi-sided dice, and a Himalayan pink salt lamp. None of them could have been confused for a delicious foodstuff, but he nonetheless labeled them: “forbidden snacks.” The simple post went viral, an idiom was coined, and a new genre spawned. Quickly, other Tumblers tried to find forbidden items that actually did look edible.

By December 30, a subreddit had been started “for things you WANT to eat but can’t.” Today it has over half a million members and generates the bulk of Forbidden Snacks memes. Forbidden Slim Jims that are actually automobile air freshener. Forbidden peanut butter that is really some goo used to wipe etching ink off of printers. A forbidden candy bar that is a firestarter. Several of these have hit the vaunted “Front page” of Reddit in the past year. Chemical explosions that look like forbidden roasted whole-head cauliflower have become particularly popular of late—in a way, they epitomize the entire appeal of this meme.

“Why humans enjoy fooling their senses I do not know, but it is a novelty that seems to be almost universal,” explains Tara (who declined to give her last name). Though she didn’t start the subreddit, she’s been moderating it since the beginning. “The sheer number of posts with utterly gross things that create a sight gag for something more edible is a testament to that.”

It’s all pretty hilarious—and, yes, most people only participate as a joke—but at the same time, it says a lot about the power of the mere visuals of food. They can compel us to watch hours upon hours of Food Network, to follow restaurant Instagram accounts in cities we’ll never visit, to take a gamble and order the shrimp cocktail off a big laminated diner menu…or to find something toxic delicious-looking. That’s why Tara sees the subreddit as a bit of a safe space. As she explains:

“If you think about it, telling people you want to munch on some dice, a rock, or a poisonous thing in real life would get you a strange look or genuine concern most of the time, not shared mirth.”

This shared mirth has led to Forbidden Snacks becoming more popular that most subreddits about actual, edible food. Tara believes that’s because they post a lot more variety of images than, say, r/foodporn; non-foodies are less likely to get bored with it. Who really needs to see another charcuterie plate or Beef Wellington when you can see a rock formation that tricks your mind into thinking it’s the most deliciously marbled forbidden steak of your life? Forbidden Snacks is, likewise, a more witty take on food content than the trite cheese pulls and fast food smash burgers that your garden variety Instagram influencer is always posting. The ironic humor fits perfectly with a Reddit community writ large that so often sees itself as geeks and social outcasts.

Of course, eventually, if you spend enough time looking at Forbidden Snacks online, they will infect your mind offline. You’ll start seeing Forbidden Snacks everywhere you go in the world. And perhaps one day, you’ll see something so delicious that, even knowing you can’t eat it, you’ll still have to have it. As Tara explains:

“I gotta admit, when I bought my last set of dice, I did so because they looked like sugar-frosted gummies.”