A washing machine heart is one that will do the dirty work of cleaning up a soiled relationship, but if you throw shoes into it, it will clunk and might stop working. Mitski explained the metaphor to BBC6 Music: "I remember trying to think of my heart pounding, and then when you put shoes in a washing machine - which I don't know if you're supposed to do but I've done before and I think we all have so we shouldn't have shame about it - and it goes du-DUM, du-DUM, du-DUM. That's what I wanted to express lyrically."

"Washing Machine Heart" wasn't released as a single but is one of Mitski's live favorites and one of her most popular songs thanks to TikTok, where it's often used in videos to convey some kind of dismay or dissociation. The line that's typically used is "I know who you pretend I am."

Mitski released the song on her Be The Cowboy album in 2018, a pivotal year for her. It was her first album to get much attention in the music press, vaulting her to a new level where she was headlining theaters and performing on national talk shows. It was too much too fast - Mitski suddenly had lots of demands on her time and a legion of fans trying to connect with her. She wasn't used to that level of pressure and scrutiny, and it took a toll on her physical and mental health. The tour for the album lasted over a year and on the last show she announced an indefinite hiatus. That hiatus lasted through the pandemic - she put out her next album, Laurel Hell, in 2022, when she resumed touring as well. While she was away, her music picked up steam on TikTok and streaming services, so she was even more popular when she came back. She had a better handle on fame by this point and was able to manage the publicity and outreach by thinking of it as a necessary evil that comes with the privilege of earning a living as a singer-songwriter.