Britney Spears and Katy Perry: Secret 'Smurfs 2' Song Collaboration
Britney wrote the song as a surprise for her two songs, who are huge Smurfs fans. The adorable duo also appears alongside their mother in the video for the song.
But, little did anybody know, there was also another famous face who made an appearance on the track.
At the premiere, Katy Perry revealed to E! News that she was one of Brit's backup singers on the track.
"Me and Bonnie [the songwriter] secretly did some background vocals on that song," she told them. "So maybe listen for our voices."
We loved the song before we knew that...but now that we know it's a Britney/Katy collab, we love it even more!
Listen to the song below and tell us if you can hear Katy in the background!