MSD

For those who say they don't "get it", here's a quick summary of the social commentary it provides.

On the surface, it's a simple characterization of the quiet acceptance of violence in our society though we condemn it publicly. We all want to express our violent urges and get out pent up anger. Toward the end, the plot shifts and shows us how the uncontrolled release of that voilent energy allows us to succumb to the appeal of nihilism as a way of righting every wrong since the beginning of society.

Strip away the in-your-face stuff and you'll find that there are two underlying messages.

First, there's the tendency to have delusions of grandeur and build ourselves up as something we aren't when we're too afraid to change what we hate about our lives and instead just deal with it like we are told we should. This encompasses the narrator's hatred of his job, and his unwillingness to accept and acknowledge his subconscious love for Marla. Second, and I think that this is something that Palahniuk wanted to convey to us on an almost completely subliminal level, is the spiral of self-destruction and violence that comes from giving in to societal pressure and repressing homosexuality. He lusts after his fictional alter ego while that ego spends long nights fucking the woman that he subconsciously understands he "should" be with.