Watch Greta Gerwig's incredible reaction to birthday 'Barbie' flash mob from Ryan Gosling

Ryan Gosling came up with the perfect idea to celebrate “Barbie” director Greta Gerwig’s 40th birthday.

On Aug. 4, the movie’s Instagram account uploaded a reel of Gerwig, who also co-wrote the global phenomenon with partner Noah Baumbach, being surprised with a Barbie and Ken flash mob courtesy of the film’s leading man.

The hilarious video begins with Gerwig laughing and covering her face as a performer suddenly starts singing Gosling’s Billboard hit, “Just Ken.” The singer is then joined by a group of Kens who stroll into the room before also belting and dancing along to the power ballad.

Next, some Barbies, donning pink outfits, of course, bounce into the room and dance to Dua Lipa’s “Dance The Night” from the blockbuster’s soundtrack.

All the Barbies and Kens then come together to do a version of the iconic group dance number from the film.

“Happy birthday, Greta!” they all cheer when the song ends.

Gerwig claps and hugs the performers as the person filming the surprise asks her to guess who sent the singing telegrams.

“I have no idea!” she says.

The director’s friend behind the camera replies, “Think of a bagpiper.” Gerwig previously revealed in an interview with SiriusXM’s “The Jess Cagle Show” that Gosling sent a bagpiper dressed in a kilt to the “Barbie” cast sleepover.

The birthday girl, looking shocked, places her hands on her face and replies, “Oh my god!” as everyone else laughs.

Gerwig appears to wipe away happy tears as the clip ends.

“As Kens know…. Sometimes the only way to express your feelings is through song & dance!” the Instagram caption said. “Ken Ryan sent these special Barbies and Kens to start Greta’s birthday with all the feelings!!”

Her reaction to Gosling’s gift sums up the response fans have had to “Barbie” for three weeks as the film holds onto the No. 1 spot at the box office.

Theatergoers have been crying and laughing while watching Gerwig’s film about Barbie’s journey of self-discovery. Fans have been particularly moved by the movie’s final scene.

“Barbie” ends with star Margot Robbie, who is “stereotypical” Barbie, leaving Barbie Land and venturing into the real world.

Robbie’s character walks into an office and tells the receptionist, “I’m here to see my gynecologist” before the screen fades to black.

Speaking about the final moment, Gerwig told USA Today in an interview published July 22 that the line was both a “mic drop kind of joke” and “very emotional.”

She explained, “When I was a teenage girl, I remember growing up and being embarrassed about my body, and just feeling ashamed in a way that I couldn’t even describe. It felt like everything had to be hidden.”

So, she decided to write a scene where Barbie was proud to visit her gynecologist, marking her first big decision in the real world.

“I was like — if I can give girls that feeling of, ‘Barbie does it, too’ — that’s both funny and emotional. There are so many things like that throughout the movie. It was always about looking for the levity and the heart,” Gerwig added.

This article was originally published on TODAY.com