Could it be just bwaaahaa? That would be Nelson Muntz from the Simpsons tag, every time something bad happens to somebody when Nelson is around (usually it’s caused by him) he points and expels a big “bwaahaa”.
Here’s his wiki
http://en.wikipedia.org/wiki/Nelson_Muntz
That sounds reasonable...thanks. (I always enjoyed the Simpsons but rarely see it anymore.)