Something unknown. Someone who doesn't have a clue. Something that is missing. From the http code for unable to locate. "4-0-4 file not found".
He hasn't got a four-oh-four. Question: Do you know where you are? Answer: four-oh-four.
by james48843 November 27, 2010
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A problem. Derivced from the Internet error message "HTTP 404: Page Not Found".
Jesus fuck, what's YOUR four-oh-four?
by Macavity October 30, 2003
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