[W]e have established a new way to read the Marxian formula ‘they do not know it, but they are doing it’: illusion is not on the side of knowledge, it is already on the side of reality itself, of what the people are doing. What they do not know is that their social reality itself, their activity, is guided by an illusion, by a fetishistic inversion. What they overlook, what they misrecognize, is not the reality but the illusion which is structuring their reality, their real social activity. They know very well how things really are, but still they are doing it as if they did not know. The illusion is therefore double: it consists in overlooking the illusion which is structuring our real, effective relationship to reality. And this overlooked, unconscious illusion is what may be called the ideological fantasy.
The fundamental level of ideology … is not of an illusion masking the real state of things but that of an (unconscious) fantasy structuring our social reality itself … even if we do not take things seriously, even if we keep an ironical distance, we are still doing them.
— Slavoj Žižek. The Sublime Object of Ideology. Verso Books, 1989. p. 32-33.