Rumblr describes itself as “Tinder for fighting.” You upload your profile picture, height, weight, location, and swipe until you fight that special someone to viciously pummel into the dirt behind the 7-11.

Rumblr isn’t real. But social media made it one of the month’s most hotly anticipated apps.

Twitter introduced me to Rumblr on Friday night. An acquaintance of a friend had retweeted a stranger who had tweeted a link to getrumblr.com (did you follow all that?), accompanied by an enticing description: “Tinder for fighting people.”

I’m running out of months to fulfill my New Year’s resolution of exercising more, and gym memberships are expensive. Rumblr, which advertised “casualty-free casual fighting for free,” promised to launch its app on Monday. If Rumblr was a hoax, it was funny. And if it was real, I was signing up.

I turned on my caps lock and tweeted the link, too: “TINDER BUT FOR BRAWLING.” In a few minutes, I’d racked up retweets from Buzzfeed’s editor-in-chief, editors at the Guardian, and tech mogul Marc Andreessen.

This is how a hoax spreads in the limited-responsibility age of “retweets are not endorsements.” The creative team behind Rumblr assembled a convincing mock-up of an iPhone app modeled after Tinder. People like me half-jokingly tweeted the link, lending the idea credibility, and it snowballed onward, pulling in wider audiences and losing context. My tweet has been viewed upwards of 43,000 times, an abnormally large audience. Tech blogs like Gizmodo, newspapers like the New York Daily News, and fighting publications like MMAJunkie all leapt at the story.

It wouldn’t have killed any of us to fact-check. Alas, Rumblr is a marketing scheme from a consulting agency called von Hughes.

“Rumblr started as a portfolio project to help us launch our creative consulting agency, von Hughes,” reads a statement on getrumblr.com. The message only appears after you try to use the app, a process that pairs you with a chatbot who types antagonistic messages at you. (“Hey, how about we just get dinner or something, instead?” I asked the bot. “You even lift bro?” the bot countered.)

This was not the first indication that Rumblr was a hoax. The site promised that the app would be “coming soon on the App Store,” a partnership Apple would almost certainly not allow. The page included screenshots from a nonexistent Instagram account. The app’s technical details—cost, terms of service, company information—were conspicuously absent from Rumblr’s too-slick website.

And nowhere did the site allude to the fact that hitting another person is very illegal in almost all circumstances.

Still, Rumblr inspired a reaction in the (admittedly overlapping) circles of sarcastic Twitter personalities and people who want to hit something. And if you’re a marketing professional hoping to seek viral fame, that audience offers a sweet spot of rage and retweets.

“We’re a team of college dropouts with backgrounds in marketing, design, and engineering. Rumblr came about organically as a funny idea amongst a group of friends, but quickly budded into an opportunity to showcase our branding skills,” Rumblr wrote in a statement. “Within a day or two, VentureBeat picked it up as a news story and, within another day or two, it spread to over two hundred news outlets globally.”

Von Hughes did not return a request for comment. They list a mailing address is SoHo, New York, if you would like to go fight them.