GREEN DAY ARE *NOT* SELL OUTS! THEY JUST...
Sell-out means when you write a certain type of music and change your music type in the midst of your career to help you sell more records. They are considered "punk", but actually, they are a mix of punk, emo, alternative rock...
In their american idiot cd, they have become more political..... but then again, they are punkers, and punk is all about protest, so yeah, they're not sell-outs...