But we can all still raise a toast to the coolest 40-something punk in the business, who hits the landmark age on Friday.
After years of rocking spiky hair and his famous crooked-toothed snarl, Armstrong shows no signs of growing up and becoming part of the establishment - he'll always be an angry young Oakland kid at heart.
He enters his 40s with a promising acting career ahead of him - a stint in his own musical American Idiot on Broadway made casting agents sit up and take notice and later this year, he'll show off his skills on TV opposite Edie Falco in Nurse Jackie.
But here's hoping Billie Joe never loses his punk edge - and in wishing him a happy anniversary, here's 10 fascinating facts about the birthday boy:
- Contrary to popular belief, his birth name really is 'Billie Joe'.
- Armstrong's song Wake Me Up When September Ends is a memorial to his father, who died of esophageal cancer in 1982.
- He met bandmate Mike Dirnt in a school cafeteria when both were 10.
- He joined the Broadway cast of American Idiot for one week, as St. Jimmy. He returned to the role for 50 performances in January 2011.
- He has two children, Joseph Marciano Armstrong (named after Joey Ramone) and Jakob Danger Armstrong.
- His closest friends outside Green Day include former Lost star Matthew Fox and My Chemical Romance frontman Gerard Way.
- He played himself in 2007's The Simpsons Movie.
- He recorded his very first song, called Look For Love, at a recording studio in Berkeley, California when he was just five years old.
- His beloved Fender Stratocaster guitar, which his father gave him as a gift when he was 11, is nicknamed 'Blue'.
- The youngest of six children, Armstrong's oldest sibling is 62.
