Songfacts®:

• This is a flirty track where Charli XCX turns up the heat, inviting her partner into a world of tantalizing mystery. She coyly challenges him to "guess" what underwear she's wearing, creating a playful tension that borders on the explicit.
• Dylan Brady, who is one half of US experimental electronic music duo 100 gecs and American singer and musician The Dare (Harrison Smith) wrote the original version.
  
  "I had an early version of that song neither of us were excited by," The Dare recalled to The Independent. "Then Charli came to town for the Met Gala, and I was throwing one of my parties that weekend, so I made a jacked-up club version for the event and sent it to her, and she was like," 'That's the song. That's it.'"
• The Dare also produced the track. The Dare first came to Charli's attention with his 2022 single "Girls," which she praised, saying it "goes off at parties." The Dare later performed as the opening act for the June 2024 Brooklyn date of Charli XCX's Brat tour. "Guess" was the first time The Dare worked with Charli.
  
  Send them to The Dare, yeah, I think he's with it
  
  Charli XCX often gives nods to her collaborators and producers in her lyrics.
• Charli recorded "Guess" for the deluxe edition of her sixth album, Brat and It's the Same but There's Three More Songs So It's Not. On August 1, it got an even hotter upgrade when she released a salacious remix with Billie Eilish. With Billie's brother, Finneas, joining the production team, the new version offers a spicier take on the original.
• On the Billie Eilish remix, the pop princesses trade suggestive lyrics, with Billie adopting her signature whispery tone for a particularly steamy verse. Billie boldly claims to know exactly what Charli's wearing, thanks to a cheeky glimpse. The bisexual singer acknowledges that Charli is straight, but if she's ever up to experiment, she is just a phone call away.
• Billie Eilish is notoriously selective about her collaborations, usually sticking close to her brother and producer, Finneas. Outside of their sibling duo, her feature credits are sparse, limited to a few tracks like Denzel Curry's "Sirens" and Labrinth's "Never Felt So Alone" – that one also involved Finneas.
• It was Finneas who sparked the idea for the "Guess" remix. Knowing his sister is a Charli XCX fan, he wasted no time in reaching out for a potential collaboration when he learned she was in LA.
• The music video, a riot of lingerie and liberated femininity, was shot on July 28, 2024, only four days ahead of its release. Director Aidan Zamiri captured the essence of the song with a playful narrative culminating in a surreal scene of the two pop stars ascending a mountain of underwear.
• Beyond the spectacle, the video also has a charitable purpose, with 10,000 undergarments donated to I Support The Girls, an American charity which collects and distributes underwear and period products to women suffering domestic violence, homelessness, and hardship.
• The "Guess" remix marked Charli XCX's second UK chart-topping single and her first as lead artist. Her previous #1 came in 2012 as a featured artist on Icona Pop's "I Love It," a track instrumental in launching her career.
  
  Meanwhile, Billie Eilish added "Guess" to her list of UK chart-toppers, following "No Time To Die" (2021) and "What Was I Made For?" (2023).
• Brat And It's Completely Different But Also Still Brat debuted at #1 on the UK albums chart, something the original version of Brat failed to do on its release in June 2024. It was Charli's second chart-topping LP, following on from 2022's Crash.
• "Guess" won Song of the Year at the Brit Awards 2025. "I'm really happy that a song about underwear now has a Brit award, very important stuff," said Charli as she picked up the gong. "I'm sure that that proves something about songwriting but I'm not sure what."
  
  Charli also took home the awards for British Album of the Year with Brat, British Artist of the Year, Songwriter of the Year, and Best Dance Act.
• "Guess" won Video For Good at the 2025 MTV Video Music Awards, beating out "Anxiety" by Doechii and the Eminem collaboration with Jelly Roll, "Somebody Save Me."