"i love brat but i absolutely despise charli xcx as a person, like how narcissistic do you have to be to believe that you deserve the headliner spot over GREEN DAY," another said.

Billie Joe Armstrong donned a Brat hat, and Tré Cool responded to Charli's "Miss Should Be Headliner" sash with a toilet paper sash of his own

Charli wore a sash that read "Miss Should Be Headliner" at Coachella's first weekend, then Green Day's drummer, Tré Cool, wore a sash that read, "Actual Headliner." It's all in good fun, but has become a Rorschach test