As referenced in South Park, a low-pitched sound that can cause someone to crap their pants. May also be used to refer to any infrasound note that can create disorientation, nausea, etc.
I'm not so sure using the brown note on those protesters was a good idea. They're still rioting and now they smell like they need a diaper change.
by connorbd@yahoo.com July 5, 2004
The name for a fictional/hypothetical sound frequency (or pitch or note) having the property that it causes loss of bowel control, and thus involuntary defecation, in humans. No actual note/sound frequency having this property has been identified as of May 8, 2008.

The term is distinct from "brown noise". In science, Brownian noise, also known as "Brown noise" or "red noise", is the kind of signal noise produced by Brownian motion. An example of Brownian noise is the sound a television speaker makes when the screen goes to static.
An article about the failed search for a "brown note" appeared in the Annals of Improbable Research.
by Keeps.making.sense May 8, 2008
a low octave sound above low E# that causes eratic bowel movements. lick my balls
by bread infection October 23, 2005
the frequency of sound that makes you uncontroably shit yourself!
i was walking down the street, saw a beautiful girl... then a noise sounded from afar and as we looked deep into eachothers eyes, we both shit ourselves uncontroably..... the brown note strikes again.
by Brandon B. And Nick K. June 10, 2006
The payment of goods or services with sheets of toilet paper. Since the corona virus out break, hoarding mentality has caused a scarcity of toilet paper, which in turn has lead to toilet paper becoming a currency in its own right.
Hey Tom, I’ll sell that to you for $2, or if your prefer to make use of our new brown noting facilities that will be 6 brown notes.
by UrbsOnCrack March 14, 2020
An extremely low frequency sound that causes Democrats to lose control of their bowels.

This refers to the January 19, 2010 US Senate election in Massachusetts to fill the seat vacated by the late Ted Kennedy. Republican Scott Brown convincingly defeated Democrat Martha Coakley, who was overwhelmingly favored to win in a state that had not elected a Republican in 40 years.
When Martha Coakley lost the 2010 US Senate election, every Democrat in America heard the Brown note.
by WHOSYERDADDY January 20, 2010
The act of slipping someone a note whilst they are making a brown in the toilet.

Often played in the workplace when you notice a colleague enter the toilets. A dangerous game to play if the person behind the door turns out not to be the intended recipient of said note.
Alex: What's Kyle doing following Martin into the toilets like that?

Richard: He's probably "Brown Noting".
by b00mdr1ve8y November 22, 2013