DESCRIPTION:
Thanks to use iMIX1337 for this little explanation:

no, the brown note is just a myth, wich started from a rumor that the note frequency called "brown" (there are also tones called pink and white and yellow) would make people shit in their pants just becasue its called "brown"

Now some kids around here are like "ZOMG! i think that i just farted!!!!!" Also, they tested the brown note myth on mythbusters, and no frequency makes human bowels vibrate so that a human sould shit in their pants. period