Similar to ground zero which is the site directly under the detonation of a nuclear weapon. Brown Zero is the area affected by a fart. Usually limited to a room unless the door was left open and it was really raunchy.
After I ate that big bowl of chili, my fiancee was caught at brown zero when I let one rip.
by computernut October 3, 2009
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Robbie pulled a muscle in his neck while trying to watch the anal beads emerge from his brown zero.

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Robbie relishes in the staccato of anal beads being ripped from his brown zero.

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To celebrate the zero he got on his exam, Robbie lubed up his brown zero before inserting enormous Korean vegetables.
by Total Penetration May 27, 2005
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