Any diehard Back to the Future fan knows that October 21, 2015, is “Back to the Future Day,” the date that Marty McFly and Doc Brown travel to the future in the second film of the trilogy. Or wait, is it July 5, 2010? Or July 6, 2010? Or June 27, 2012? You may have seen conflicting photos on your Facebook page over the years of random future dates Doc and Marty traveled to from 1985, all splayed across the dashboard display of their time-traveling DeLorean. These posts you’ve seen? They’re a pack of lies. Rest assured, Back to the Future’s 30th birthday is this year, and the real Back to the Future Day on October 21, 2015, is finally happening.

For the past half decade, the internet been cheerfully hoaxing casual Back to the Future fans on exactly when Doc and Marty go to the future. The distance from hoax to meme is only a few dozen gullible aunts and old high school buddies. This meme began with a 2010 tweet by British movie magazine Total Film. The tweet told followers, wrongly, that July 5 was “Future Day,” even including the hashtag “#futureday” to give it some gravitas. The magazine followed that up with a Photoshopped Twitpic image to prove it.

Those who weren’t BttF superfans or didn’t have enough time to double check the date on their DVD copy of the movie happily went along with it. More than 1,000 people retweeted or favorited the tweet, including — according to Total Film — Elizabeth Banks, Colin Hanks, Joe Jonas, Ivanka Trump, and BttF producer Frank Marshall. But rigorous geeks pointed out the error, and the jig was up. In a follow-up post the next day, Total Film confessed.

“A casual office conversation brought up the ‘fact’ that 5th July 2010 is referenced in Back To The Future (though Doc and Marty never actually go there), so sensing a bit of fun for our Twitter feed (and without checking) we posted the Tweet,” the magazine explained. “So apologies, film fans. We were wrong. It seems some lax research and average photoshop skills go a long way on Twitter these days.” Things should have ended there, but another photoshopped image popped up, updating “Future Day” to July 6. It made the rounds. (People love to share more than they love to fact-check.)

The Guardian’s Catherine Shoard, for one, saw these jabs at the fabric of a classic sci-fi comedy as downright heretical. Who were these people, after all, to rewrite the history of a time-travel film?

Back to the Future is a film so powerful, especially if it hooked into your brain at an impressionable age, a film so intimately wedded to the idea that a split second can make all the difference,” she wrote, “that to shuffle its finely wrought construction in this way feels like sacrilege. Even if it was, in this instance, affectionately, even jubilantly, intended.”

Since the original caught on, random corners of the internet have taken the meme in as their own by changing the dates at will. (People love to plagiarize lies more than they love to come up with their own hits.) A photoshopped image saying “Today is the day Marty McFly arrives when he travels to the future” began popping up on Facebook bearing the date July 11, 2012. Photoshoppers hijacked that, and other searches bear the same image with a range of different dates: February 4, 2013; March 22, 2013; October 21, 2013; October 14, 2012, and so on.

The most popular alternate version seems to falsely label June 27, 2012 as Back to the Future Day, which stemmed from a post made by UK-based mobile app company Simply Tap. The second round of the meme gained coverage in major media outlets, and forced Simply Tap’s social media manager, Steve Berry, to admit that the post was faked on purpose as a way to market the Back to the Future Blu-ray for one of the company’s clients.

“We promoted the image fully confident in the knowledge that everyone was familiar with the original hoax from a couple of years ago,” Berry told Mashable in 2012. “We figured that no one would fall for the same joke twice, so the caption was deliberately replicated word for word so people would get the reference.”

A simple search on Twitter shows people admitting any other random date as Back to the Future Day as well.

Though the exact 30th anniversary has technically passed (the film was originally released on July 3) the kitschy charm of holding the movies’ three-decade birthday festivities this year on the date Doc and Marty travel in time gives an added bonus to fans. Thankfully they’ve embraced the absurdity of the meme, with full websites dedicated to reminding you that this October 21 is Back to the Future Day, and other trolling sites pulling in more easily deceived people willing to accept that any day is BttF Day.

It’s an enduring but annoying meme, and thankfully it won’t be around for much longer.

Photos via www.facebook.com/simplytap/photos, www.backtothefuture.com