Let's face it — Green Day hasn't been a "punk band" for quite some time. So, when lead singer Billie Joe Armstrong took the stage at Friday's iHeartRadio festival in Las Vegas to unleash a profanity-laden rant against Justin Bieber and festival promoters, observers assumed the stunt was simply a halfhearted attempt by the 40 year-old to inject some juvenile "punk" ethos back into the band's vocabulary.
Today, however, it turns out that the Green Day frontman's onstage meltdown was fueled by something more than middle-aged angst. Reps for the band announced today that Armstrong will enter rehab for "substance abuse."
The news comes on the heels of several bizarre incidents involving Armstrong — including a recent hospitalization for an undisclosed "illness" during Green Day's Italian tour earlier this month.
Video of Friday's incident shows Armstrong rambling against the festival promoters' supposed decision to cut Green Day's set short. (A statement from the band, also released today, admits iHeartRadio had no plans to give Green Day less time to perform.)
All upcoming Green Day performances are postponed until further notice.
Watch all of Armstrong's rant from Friday below: