Before every international series, each country provides the other with a list of "banned" words/phrases/sledges that must not be used (to allow for cultural differences).
I was actually joking when I suggested this a few days ago, but there you go!
Monkey appears on the list. Based on the current facts, Harbhajan must be cleared as there is no actual evidence beyond any reasonable doubt that he said it.
The B word does NOT appear on the list - the BCCI did not nominate it as a banned word.
That said, the simplest way to deal with it is to ban all sledging and let the bat/ball do the talking.