Lyric discussion by green_day_FREAK 

Cover art for 27 lyrics by Pinhead Gunpowder

27 is also the number of a band called 'The Riverdales'...they're on Lookout! records...all members are ex (or also) members of Screaching Weasel (Tré and Mike's band...)...and their first album was released in June 1996 and was produced in part by Billie Joe...

so it means that for sure that's what the 27 means...think i broke the mystery here...loll

Nyways..had to write that...

That's correct. I've got an old interview with Billie where he mentions getting the 27 tattoo to celebrate the Riverdales album.