The first rule of fight club is, you do not talk about fight club. That is also the second rule of fight club. There are ten rules to Fight Club, but usually only the first one is remembered.
Fight Club was published in 1996, and the movie of the book was released in 1999. At the time, the book was widely received as a sophisticated work of cutting social commentary. The movie crossed the book over to a wider audience, and the first rule of Fight Club became something of a meme. In fact, it became a subcategory of meme known as a snowclone: where would be wits would say, for example:
"The first rule of making a pineapple upside-down cake is, don't talk about making a pineapple upside-down cake."
Which of course, quickly lost its humor value, although perhaps now it has become so cliche that it is funny through the unhipness of it. I haven't been keeping track.
Just as it is ironic that Fight Club, which may have been a sophisticated look at American mass culture, was transformed into a simple work of adolescent rebellion, it is ironic that the single most publicized and remembered part of Fight Club is the fact that it shouldn't be publicized.