So it turned out that the Muggle rip-off artist was none other than notorious dog-owner Billie Joe Armstrong. Otherwise known as the lead singer of Green Day.

It was one of those spectacular moments where the boundary between the real world and the magical one collapses in the funniest way imaginable.

Picture it: The year is 2003. Billie Joe is walking his dog down the boulevard, stops to let the poor thing do a poop, and—emo hippie that he is—probably tries to pick up a piece of litter. And then, out of nowhere, he and his cockapoo get magically yoinked across New Jersey. Next thing he knows, he’s onstage, being treated like a novelty act in front of a crowd of witches who are way too invested in Celestina Warbeck’s love life. By the end of the night, the Men in Black show up, wipe the experience from his mind, and send him home.

But here’s the thing: the dog remembers everything. 

So for months, Billie Joe is reliving the concert in broken little dream-fragments. The boulevard. The stage lights. The melody he can’t place. That uncanny feeling. All of this eventually spills out during a songwriting session.

And that’s how the man ended up writing Boulevard of Broken Dreams—the ninth-highest-selling single of the entire decade. No wonder Celestina was pissed.

And the best part? The timing fits. American Idiot dropped in September 2004, exactly halfway between Order of the Phoenix and Half-Blood Prince. Rowling would have been in the final polishing stages of HBP during that window, and that song was everywhere. Grocery stores. Radio stations. LimeWire playlists.

Trust me on this: I was a teenager at the time. The demographic overlap between Green Day fans and Harry Potter readers in 2004 was enormous. Rowling knew her audience. And Boulevard of Broken Dreams? Melancholic and defiant and dramatic as hell. It was music for Muggle-borns.

If there’s a takeaway here, it’s this: treat everything you find on the Wizarding World Online Archive like it matters. Nothing on that site is posted without intention—but none of the truly wild, secretly brilliant connections are ever spelled out. Canon and extended canon only come alive when the reader brings their imagination to the table.

Sometimes the truth is hidden in plain sight, tucked into the margins of the most obscure footnote imaginable. And sometimes, apparently, it’s hiding inside a Green Day single from 2004.

You just have to be ready for the truth to be gloriously absurd.