Camila Cabello and Shawn Mendes' new song, "I Know What You Did Last Summer," has fans all up in a frenzy, and the story behind it is kind of awesome! It turns out, Taylor Swift played a pretty major role. They wrote it backstage at one of her The 1989 World Tour shows.

In fact, it seems like the singer has been writing music that she doesn't always fit with Fifth Harmony's style (and she's happy to be able to finally release some of her own original music). She says that she's been "writing songs in hotel rooms for years" and that it means so much for her to "get to share" "I Know What You Did Last Summer" with her fans.

We can't wait to hear it!

Are you excited to hear their song? Let us know in the comments!

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