Billie Eilish was home-schooled by her screenwriter mom Maggie Baird. When Billie was 12, her mother gave her an assignment to write a song inspired by a movie or television show. The tune she came up with, "Fingers Crossed," is about a zombie apocalypse, inspired by her favorite TV series at the time, The Walking Dead
As she watched the show, Billie wrote down lines that she thought were good hooks and lyrics. Although not intentional, "Fingers Crossed" came out more like a longing heartbreak song. But she confirmed to Junkee
, it is indeed "about zombies."