Finneas [1]appeared on The Tonight Show Starring Jimmy Fallon [2] on Monday night to discuss all things music, and as usual, he sounded terribly casual while discussing he and his sister, Billie Eilish [3]'s, meteoric rise over the past year.

But before performing his soulful bop, "Let's Fall in Love For the Night," in front of the the live audience, he revealed there area few everyday sounds in Billie Eilish [4]'s songs that are so well hidden, you probably never even noticed them. The first is the sound of a dentist's drill — you know the high pitched squeal that sounds like it's drilling into your brain — that's hidden in "Bury a Friend," and Australia's crosswalk sound that's oddly catchy is buried somewhere in "Bad Guy." Watch the full video above to find out exactly where the everyday sounds are hidden, and be warned, once you've listened, you just can't unhear it.