Last summer, Shawn Mendes and Fifth Harmony’s Camila Cabello hit the road together as openers on Austin Mahone’s tour. In that year since, the pair — who are 17 and 18 years old, respectively — have released lauded debut albums and scored chart-topping singles with Mendes’ “Stitches” and Fifth Harmony’s “Worth It.”
“I honestly remember so clearly the first day we met,” Cabello reminisces. “He was just playing with a guitar, and I was like, ‘Hi! Nice to meet you.’ We didn’t really hang around much during Austin’s tour. It was Shawn’s first tour ever, so he was constantly working, and if he wasn’t working, he was in his bus playing guitar and being a loner.”
This past summer, Cabello and Mendes reconnected backstage at one of Taylor Swift’s concerts. Mendes has opened for the pop star, and Cabello attended with fellow Fifth Harmony member Ally Brooke. “That was the first time we had ever really spent more than a few minutes talking to each other,” she says.
“We were just backstage hanging out,” Mendes adds the next day. “I pulled out my guitar and we were just messing around, not really thinking about writing a song.”
The casual meeting led to the pair writing “I Know What You Did Last Summer,” a soulful, conversational pop duet that has the friends evoking the styles of their favorite artists, like Ed Sheeran and John Mayer. For Cabello, the dramatic lyrical dialogue stemmed from real-life heartbreak.
“At the time, I was talking to a guy that I liked, and a friend called me two days before we wrote the song and told me he had been hitting her up and trying to flirt with her as well,” Cabello reveals.
“[Shawn and I] started talking about that in the song. It’s about finding out that somebody had been cheating on you, and the song is that moment right before you confront that person where you both know what’s next, but it’s killing the both of you.”
For both, the song title’s reference to the 1997 horror movie of the same name starring Jennifer Love Hewitt and Freddie Prinze Jr. was purely coincidental. “When we were writing, I remember one of us just kind of blurted out the phrase ‘I know what you did last summer,'” Cabello says. “I remember while we were recording, we knew that it was a movie title because one of our friends showed us the trailer for it.” The pair looked to see if they could get any lyrical inspiration from the movie, but the song and film didn’t exactly connect. “We were like, ‘OK, no. This is a completely different thing!'”
Another reference within the song’s lyrics was also unintentional, though it ended up giving Bill Withers a songwriting credit. “When Camila did the ‘I know, I know, I know,’ I don’t think she had even heard [‘Ain’t No Sunshine’] before, which was funny,” Mendes says with a laugh. “I knew the song, though.”