Green Day frontman Billie Joe Armstrong is going from rock star to TV star. Armstrong will guest star in the fourth season premiere of Showtime's 'Nurse Jackie'.

The rocker's role hasn't been revealed yet, but sources whisper he'll play John, a 45-year-old "bada---" and drug user. John has a wife and kids who don't talk to him and is chasing the "ultimate high."

Armstrong has shown a flair for theatrics in the past, but his roles were mostly behind the scenes. Green Day's album 'American Idiot' spawned a Grammy-winning Broadway play (that Armstrong appeared in) and the play is currently being adapted to a feature film -- possibly starring Robert Pattinson!

Has Armstrong caught the acting bug? Maybe! Executive producer Richie Jackson tweeted a photo of Armstrong with Nurse Jackie herself, AKA actress Edie Falco, writing, "Edie and our new cast member @BJAOfficial! Wait til you see the season premiere!"

The "cast member" term is what has us thinking. If Armstrong were only going to appear once, wouldn't they just call him a "guest star"? If Armstrong's acting chops are as good as his songwriting, singing, and guitar wielding, we can't wait to see what Showtime has in store for us!