Brad Pitt and Joey King formed a band with their 'Bullet Train' co-stars.
The cast - which also includes Aaron Taylor-Johnson and Sandra Bullock - got along so well that they decided to join forces for a musical group.
Joey, 23, told Entertainment Tonight: "We get along so well, it's just really, really fun. We've got Brad, who just sets the tone. He's an amazing, talented leader of our band.
"We have a whole band name and everything! We're called Naked Below the Line. I don't even remember the story behind the band name!
"I don't know how it happened! We just have the most wonderful time together."
Aaron, 32, joked that the band are still working out what musical instruments to play.
He said: "We're still figuring things out. Like, we're still experimenting."
And Brad quipped that the band's name implies they "just wear shirts."
He said: "Joey's gonna be our front person. And we're all kind of doo-wopping in the back."
Meanwhile, Joey previously admitted she felt like a "fish out of water" with impostor syndrome when she arrived on the set of 'Bullet Train'.
She said: "I've been acting for almost 19 years now, which is actually insane, but I feel like this movie, stepping onto this set, I felt like I had just touched down in Los Angeles and it was my first [movie]. I felt so fish out of water, imposter syndrome, I was like, 'What am I doing here? I don't deserve to be here.'"
However, Brad, 58, instantly put her at ease and she was "so comfortable" in his company.
She continued: "But working on this movie with the entire cast and of course Brad, I mean he's f****** Brad Pitt at the end of the day, we love Brad Pitt, it was truly an honour, not just because they're so talented and have such cool careers, but because they're the coolest humans to work with. Brad became someone that I was so comfortable with and feel so lucky that I was able to share this time with, I just absolutely adore him."
Joey loved that her character of The Prince was "gender-swapped".
She said: "First of all, I loved my character, everything how she was written, how villainous she was, but then also that her name is so strong and powerful. Like you said, they gender-swapped me, but they kept her name as The Prince. It made me so happy because I was like, 'This name feels like the perfect way for me to build the character around her because it made me feel so strong and powerful'. I knew who I wanted her to be based on how strong I feel when I say, 'I'm the Prince'."
Brad stars as assassin Ladybug in the flick, who wants to give up the life but is pulled back in by his handler Maria Beetle (Bullock) in order to collect a briefcase on a bullet train heading from Tokyo to Kyoto. Onboard the train, he and other competing assassins discover their objectives are all connected.