Taylor Swift literally loves nothing more than leaving fans secret messages and easter eggs in her work, so it may not come as a surprise to you to learn that there's even one in her Zayn Malik collab 'I Don't Wanna Live Forever'.
Now before we get into what exactly the Buzzfeed lot have unearthed, let's take a moment to assess past evidence leading up to this moment.
T-Swift's lucky number is 13, but it's so much more than just a number. Tay herself has previously explained that she used to write it on her hand before gigs, and that she can only possibly win an award if she's sat in the 13th row.
She was also born on December 13, her 1989 album had 13 tracks and her debut went gold in just 13 weeks. So yeah, the number is a big deal in her world.
Which brings us to now, as it's revealed that Taylor sings a certain lyric in the 50 Shades Darker track exactly 13 times. Yep, "Until you come back home" was the line in question, and we're obsessed that Tay still does this!