AJR’s song “Joe” is the 5th track of their album, OK ORCHESTRA (released March 26th 2021).

The song tackles the childhood inspiration or idol in someone’s life, or more personally, the person Jack sings about whose name is also the title of the song, “Joe”.
Asking Joe if he thinks he’s now cool, somewhat flexing on whoever Joe is by talking about his accomplishments.

It’s also mentioned that Joe could be or could not be a placeholder name for someone they have encountered in their life.

Jack mentioned in their live acoustic livestream that Joe was someone in Ryan’s life who he admired and looked up to and wanted to be like him, rather than it being a childhood bully contrary to popular belief. (March 26th 2021)