MartinRandom said: The japanese have a sound-effect word for standing in a wave of diarrhea. :(
It was a joke, that's not what ブアッ means. I cannot discount the possibility that they do have a sound effect for standing in a wave of diarrhea, though.
*sigh* ブアッ says "BWAH!" A common reaction to one's outer clothing being completely blown off in public by a wind spell that was probably supposed to be a much lighter color.
Learn2katakana, it isn't hard. There's only like 45 of them.