 While writing at his home studio , Armstrong worked on a cover of The Who 's 1966 mini @-@ opera " A Quick One , While He 's Away " ; Green Day recorded a full @-@ band version of the song during the album sessions . Vig noted that frustrations would sometimes cause delays in the recording process for 21st Century Breakdown . Armstrong kept his lyrics closely guarded and intentionally mixed his demos so that the vocals were low in the mix and thus unintelligible to the other band members . It was not until late 2008 that he chose to share his words with Cool , Vig , and bassist Mike Dirnt by sitting down with them and reading the entire album 's lyrics aloud in order . The band members made the finishing touches on the album in early April 2009 and claimed that its release would lead to a " kind of ... post @-@ partum depression " . 
