Walking Contradiction song meaning

The narrator of this song claims to be a walking contradiction and brings up examples of how he refutes and opposes himself - "I'm a smart ass, but I'm playing dumb", "I have no belief, but I believe..." But aside from that he's also mentioning the contradictions of life, and how "standards are set and broken all the time". Indeed, it seems that the world is contradicting itself in so many ways. How often do we complain about the ever-present Murphy's Law and Catch 22? "Losers winning big on the lottery, rehab reject still sniffing glue". Life itself is a walking contradiction.

Certain parts of this song might have been inspired by the side effects of success.
"I'm a victim of a Catch 22" - show-business is full of those catches. When your music is good, a lot of people start liking it - and then they say you sold out and start hating the exact same things they used to like about you before. And somehow by doing what you like, you turn into something that you hate. "My wallet's fat and so is my head" - honest words about what might happen to you after you unexpectedly get rich and famous, not everyone can stand that test.

It is believed that there is no such thing as "a popular punk band", yet that's exactly what Green Day managed to become. A walking contradiction.