Someone who sneaks into a residence in which the dweller lives by themself, then deficates in their toilet leaving no visable toilet paper and then does not flush.
Jessie got home to her apartment after a long day at work. She stepped into the bathroom to take a shower when she spotted the foreign monster in the toilet bowl... she knew then the brown ninja had struck again.
by dsackaroo January 23, 2013
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LEGO™ Man: “Hey have you heard that the Brown Ninja sacrificed Kai to Satan?”

LEGO™ Man 2: “Yeah, sadly they didn't get along since Brown Ninja was a god.”
by PseudonymDefinitionPleaseOrDie September 14, 2019
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leaving a foul oder, usually in the form of a sbd fart for someone to walk into, unsuspectingly.
I just left a brown ninja for jeremy to walk into.
by rossta January 26, 2005
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One who is a master of the brown eye. Can stealthily attack from behind with a thrusting motion.
Why does Brett have to be suck a brown-eyed ninja?
by Dan September 23, 2003
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