Greendayism 

A so-called religion that involves people who are totally obsessed with Green Day.

Green Day Fan: OMG I don't follow Jesus, I follow Greendayism!! DUH!

Greendayism by xX-dismal-Xx May 28, 2007

GreenDayIsTheBest 

He says "an awesome green day song" to every song he's defined, even if it's not that good, and it seems he only has their International Superhits.

an awesome green day song

GreenDayIsTheBest by TheLostDude December 31, 2004

Greendaying 

n. A euphemism for masturbation in reference to the song "All By Myself." Used mostly by ugly-ass high school girls passing notes at the Twins game next to the left field pole.

Ugly Girl 1: I've been Greendaying every once in a while, but i really don't think about Jesse all that often. I swear.

Ugly Girl 2: Eeeeeww!!!

*stupid bitches*

Greendaying by paddlenaked June 27, 2004