The music is said to be inspired by 1960s rock 'n' roll and the band plan to release a free six-track EP soon.
Three songs titled 'Mother Mary', 'Ruby Room' and 'Stop, Drop and Roll' have already been posted on the band's MySpace page.
Rumours are circulating that it isn't just Billie Joe on the tracks, but the other two members of Green Day as well. If so it ain't the first time the wily punks have recorded under a different moniker either. They previously released 'Money Money 2020' under the name The Network.
Armstrong has confirmed that Green Day will hit the studio in January to begin the work on 2004's 'American Idiot' follow-up.
Check out the tracks here and tell us what you think! www.myspace.com/foxborohottubs