Why is ‘Barbenheimer’ having such a cultural moment?

It started as a joke: A candy-colored feminist comedy about a beloved toy and a biopic about the man who created the atomic bomb premiering on the same day.

But initial jabs, tweets, and memes about “Barbenheimer” — the unofficial crowdsourced campaign for a double-feature of the Oppenheimer and Barbie films — have become a profitable reality. Ahead of the films’ premieres on July 21 (technically the evening of July 20 at many theaters), we explain.

The films share a premiere date, but they’re wildly different.

Oppenheimer is a biographical thriller directed by Christopher Nolan about J. Robert Oppenheimer, the theoretical physicist who helped the United States develop the first nuclear weapons. It is based on the book American Prometheus by Kai Bird and Martin J. Sherwin and stars Nolan favorite Cillian Murphy (Inception, Peaky Blinders). Other cast members include Florence Pugh, Matt Damon, Emily Blunt, and Robert Downey Jr.

Meanwhile, Barbie is director Greta Gerwig’s take on — and the first live-action feature about — the Mattel toy company’s Barbie doll universe. It stars Margot Robbie as the namesake doll and Ryan Gosling as Ken. Details are scarce, and Gerwig is expected to have some tricks up her sleeve, but the gist of the film will surround Barbie and Ken leaving Barbie Land for the real world. The film, featuring a highly anticipated pop soundtrack, also stars America Ferrera, Kate McKinnon, and Will Ferrell.

When the films’ coinciding premiere date was announced, memes celebrating the chance to see both on the same day popped up. Moviegoers joked about the seemingly polar opposite movies, likening them to different personalities or genders.

According to the New York Times, online searches for “‘Barbenheimer’ T-shirt” brought tens of thousands of results and prompted Etsy designers to take advantage of the moment.

As noted by the Times, “Barbenheimer” has become a fan-powered marketing tool that film studios are rarely able to plan for or create themselves, in turn, generating buzz for both films, at a time when the film industry often struggles to get people to theaters.

Film industry analyst Robert Mitchell told the Times it’s likely because the films are “so vastly different.”

The proof is in the ticket sales. Last week, AMC Theaters said that more than 20,000 people purchased tickets to see both films on the same day, back-to-back.

According to Variety, AMC saw a 33% increase in the number of guests who “created their own double feature” since tickets went on sale. On social media, Philadelphians attending both films have been documenting their game plans.

Cassidy Tarullo and her fiancé are seeing both films Thursday. The plan is to lead with Barbie at 3 p.m. and then see Oppenheimer at 9 p.m.

“We’re big movie people so we simply love going to opening days,” she said. “But it was also important to me to contribute to Barbie’s opening weekend earnings.”

Christie Corso of West Kensington and her partner, Drew Barkley, are self-described “cinema nerds.” They plan to see Oppenheimer “the way it must be seen,” in IMAX on 70 mm film, followed by Barbie. Corso said part of their motivation to see movies at the theater is the recent Writers Guild of America and SAG-AFTRA Hollywood strikes.

“The summer movie season, and the theatrical experience, we believe has to be preserved, even though we understand that going to the movies has become very expensive,” she said. “Why would we let the silver screen die? What better way to do it than to commit to a double feature like the old days of cinema?”

» READ MORE: What the SAG-AFTRA strike means for your favorite movies and TV shows

Even West Philly comedian Connor King is getting into the “Barbenheimer” spirit.

On his Instagram and TikTok accounts — which boast a combined following of nearly 350,000 followers — King posted a video of him dressed in black leaving an Oppenheimer screening, before quick-changing into a Barbie muscle tee. He captioned the post: “Match my Kenergy.”

In some ways considered a relic from the past, double features are usually intended for films that — unlike this pairing — have things in common, like a genre or director.

Examples of double features include Quentin Tarantino and Robert Rodriguez’s double billing of their films, Planet Terror and Death Proof, under the name Grindhouse in 2007. Double features can also be used as a marketing tool. In 2009, ahead of Toy Story 3, movie theaters rereleased Toy Story and Toy Story 2 as a double feature. In 2010, the Twilight series did a similar rerelease ahead of The Twilight Saga: Eclipse.

But a fan-driven double feature surrounding completely different movies is less precedented. It’s unclear if a similar crowd-generated campaign has ever drummed up this much hype.

In 2008, another type of “Barbenheimer” occurred: The Dark Knight, also directed by Nolan, and Mamma Mia! dropped on the same day.

As noted by GQ, “The Dark Mamma” didn’t take off the way “Barbenheimer” has. But, in recent months, a series of viral tweets about the coinciding release date brought new attention to the films.

A Twitter thread by the pop culture account, @notgwendalupe, posted a list of other similarly conflicting movies with overlapping release dates. The list included 10 Things I Hate About You and The Matrix in 1999 and She’s the Man and V for Vendetta in 2006.

Whether because of less-robust internet communities or the fact that “Barbenheimer” features two movies anticipating critical acclaim, none of the previous conflicting premieres inspired a double-feature campaign.

Experts say memes about “Barbenheimer” are behind the double feature’s popularity.

One of the earliest viral “Barbenheimer” tweets was published in January when Indiewire film critic David Erlich tweeted “7 months and 21 days until ‘Barbenheimer,’” according to Know Your Meme.

Know Your Meme says “Barbenheimer” as a double feature gained traction after memes and fan art “used images that were both pink and black (correlating with the color palettes of both films), as well as images that involved both explosions and girlie aesthetics.”

Barbie runs 1 hour and 54 minutes while Oppenheimer is slated for 3 hours — make sure to account for that when purchasing your tickets.

Theater chains including AMC, Regal, and Cinemark are showing both films. You can check sites like showtimes.com to plan.

In Philly and the surrounding region, other theaters scheduled to screen both movies include Ritz V, Studio Movie Grill Upper Darby, Movie Tavern Flourtown, Ambler Theater, and Penn Cinema Huntingdon Valley.

The Philadelphia Film Society is showing both movies, but at separate venues, according to its calendar.

Juanita Cortés said she and her husband enjoy supporting the Film Society. So, they will see Barbie at PFS’ East Theater on Second Street and then head to AMC in the Fashion District for Oppenheimer later that day.

They opted for the AMC because it will use a Dolby screen and sound. True cinephiles are factoring in projector, film, and sound quality when selecting a theater.

“We are excited for this cinematic event,” Cortés said. “The movies are so back.”

While official Oppenheimer celebrations are hard to come by, plenty of local groups and venues are celebrating Barbie’s debut.

On Tuesday, the Dermacenter Medical Spa on Pine Street is hosting a free Barbie Party with prizes, aesthetician demonstrations, and cocktails. TLearning Express Toys in Collegeville is hosting a free Barbie “meet-and-greet” kids event Wednesday.

In Germantown, plant store Pomelo will host a ticketed premiere party with cocktails and flower crowns Thursday. There’s also a Pride Barbie watch party in Neshaminy and a roller skating party in Hatfield.

The appropriately named bistro Blondie in Manayunk has transformed into “Barbie World” and will stay that way until the end of the month, with themed decor and menu items.

This is perhaps the most critical question and one being debated.

On social media, some say Oppenheimer should be viewed first because people “know how it ends.” Others say they want to see Barbie first because it probably ends on a lighter note than a movie about nuclear weapons.

A new report by Digital Third Coast used Google search terms to determine which of the two films consumers were more excited about in each state. According to the survey, Oppenheimer has the lead in Pennsylvania.

On Reddit, the debate rages on. Some say they’re closing out with Barbie as a “palate cleanser.”

“We’ll do Oppenheimer first so if we leave feeling very down — as they’re practically advertising — Barbie will make us laugh and feel good on our way home,” said Philly-based Sara Antosiewicz about her and her husband’s plan. “We both genuinely want to see both and think the contrast is really fun.”