[…] a subliminal message technique, a word that the majority of the population since early childhood has been trained to ignore (and trained to forget both the training and that they are ignoring it), but which they associate with a vague sense of unease. Upon seeing the word, readers experience a panic reaction. They then subconsciously suppress all memories of having seen the word, but the sense of panic remains. They therefore associate the unease with the news story they are reading. Fnords are scattered liberally in the text of newspapers and magazines, causing fear and anxiety in those following current events. However, there are no fnords in the advertisements, thus encouraging a consumerist society. Fnord magazine equated the fnords with a generalized effort to control and brainwash the populace. To “see the fnords” would imply an attempt to wrestle back individual autonomy, similar to the idea of reading between the lines, especially since the word fnord was actually said to appear between regular lines of text.
— Wikipedia