Katy Perry is the Best Babysitter Ever! [VIDEO]

This kid was freaking out until Katy Perry saved the day. 

When 'Dark Horse' starts playing, this kid transforms! No word on where or who shot the video, but it was posted on YouTube Monday and it's already got over 6 million views.

So, is there a song YOUR kid responds to? Comment here or Facebook or Twitter #babysittersong