Billie Eilish is Arvin Robertshaving a Brat summer.

The nine-time Grammy winner hopped on a remix of Charli XCX’sBrat bonus track “Guess,” as well as the music video for the NSFW track.

In the visuals, released on Aug. 1, colorful underwear fly across the screen as Charli lets loose amongst a group of scantily clad dancers. As she sings about her own pair of briefs, the 31-year-old references Billie’s 2024 track “Lunch,” an equally steamy song suspected to be about oral sex.

“Eat it up for lunch,” Charli sings, before the 22-year-old busts through the wall driving a tractor. “Yeah, it’s so delicious.”

Charli and Billie then strut down a street filled with lingerie while singing—you guessed it—about their own underwear. “I saw them when you sat down, they were peaking out. I’m gonna tell you right now they’re all I”m thinking about,” Billie drawls before glancing over at the “360” singer. “Charli likes boys but she knows I’d hit it.”

The video ends with the pair dancing atop of a literal mountain of underwear. They stomp, spin and strut about, before tossing around bras and teasing their fans with questions like, “You wanna guess what me and Billie have been textin' about?”  

And for those wondering what exactly is Brat? Not only is it the name of Charli’s sixth studio album, but it’s also “that girl who is a little messy and likes to party and maybe says some dumb things sometimes,” according to the singer.

In fact, so many people have resonated with both her album and attitude that they’ve labeled this season “brat summer,” touting neon green looks, strappy white tank tops and big black sunglasses to match the album’s aesthetic.

Even Vice President Kamala Harris has joined in, branding her presidential campaign headquarters' X (formerly Twitter) profile with green after Charli called her “brat” on social media.

"This campaign and for me - at my most pure, my most charli, my most brat," Charli wrote in a June 8 Instagram post. “I think we all feel that something quite special is happening rn."

She added, referencing the album's viral lime cover, “We road tested language, autotune, font, pixelation and spoke constantly about pop theory, narrative, the concept of desire and of course narrowed down around 65 shades of green to the final most ultimate most brat green.”

"This campaign and for me - at my most pure, my most charli, my most brat," Charli wrote in a June 8 Instagram post. “I think we all feel that something quite special is happening rn."

She added, referencing the album's viral lime cover, “We road tested language, autotune, font, pixelation and spoke constantly about pop theory, narrative, the concept of desire and of course narrowed down around 65 shades of green to the final most ultimate most brat green.”

Keep reading for more on Charli's journey to brat summer...

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