You may know Billie Jo Armstrong as the charismatic leader of Green Day, the pop-punk outfit that has supplied hits like "American Idiot" and "Basket Case" since their formation in 1987. But did you know that Armstrong, who is celebrating his 50th birthday today (Feb. 17), once recorded a record in honor of one of country's most influential duos?

The surprising project was born after the award-winning guitarist and vocalist was first introduced to The Everly Brothers' 1958 album Songs Our Daddy Taught Us. The record, which many credit as being ahead of its time in mixing folk and country traditions with rock and roll stylings, made a big impact on Armstrong.

"I was listening to it every morning for a while off and on," Armstrong told Stereogum in a 2013 interview. "I thought it would be cool to remake the record because I thought it was sort of an obscure thing and more people should know about it, but I really wanted to do it with a woman singing because I thought it would take on a different meaning — maybe broaden the meaning a little bit — as compared to hearing the songs being sung by the two brothers."

Armstrong's wife, Adrienne, suggested he team up with acclaimed jazz-pop artist Norah Jones for the project. Soon after, Armstrong and Jones headed into the studio with a vague idea for their collaboration. They started by recording "Roving Gambler," the first track from Songs Our Daddy Taught Us, and things quickly came together from there.

The result is Foreverly, a modern reinterpretation of Songs Our Daddy Taught Us in its entirely. Armstrong left behind his intense, growling vocals for sweet and impactful harmonies that mesh perfectly with Jones. The album's first single was "Long Time Gone," which showcased the duo's dedication to paying homage without making the songs feel fake or overdone.

It's understandable to country or folk fans to feel hesitant when they hear a punk legend is suddenly going country. In this case, it's clear that Armstrong and Jones put thought and heart into the project.

Overall, they kept the instrumental accompaniment simple and close to the original recordings, which placed focus on brothers Don and Phil Everly's hypnotic harmonies. On tracks like "Kentucky," Armstrong and Jones add just enough flare and modern production elements to make the song feel up to date.

Foreverly, which was released in 2013, stands as an authentic and heartfelt tribute to one of the genre's most impactful acts. The project led to another surprising country collaboration, too. Armstrong joined Miranda Lambert to cover The Everly Brothers' "When Will I Be Loved" at the 2014 Grammy Awards to honor Phil Everly, who passed away earlier that year.

In 2016, Lambert paired up with Armstrong and his Green Day bandmates for a duet version of their song "Ordinary World" included on their Greatest Hits: God’s Favorite Band album.

Although these are Armstrong's only moves into country music so far, he has spent his entire career pushing the boundaries creatively. Outside of his work in Green Day, Armstrong has created a myriad of businesses including a guitar shop and coffee brand. He's also well-known for his work adapting Green Day's award-winning album American Idiot into a Broadway musical, which won two Tony Awards and wide-spread critical acclaim.

See the Most Played Country Song from the Year You Were Born

Who had the most played country song during the year you were born? This list is a fascinating time capsule of prevalent trends from every decade in American history. Scroll through to find your birth year and then click to listen. Some of these songs have been lost through the years, many of them for good reason!

Men named Hank dominated early before stars like Freddie Hart, Ronnie Milsap, Willie Nelson Clint Black took over to close the 1980s. More recently it's been Tim Mcgraw, Rodney Atkins, Kane Brown and Morgan Wallen. Did the most-played country song from the year you were born become a favorite of yours later? All info comes from Billboard's country airplay charts.