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
1 more definition
I just left a brown ninja for jeremy to walk into.
by rossta January 26, 2005