Baka essentially translates to "horse-deer". The story behind baka is of a Chinese emperor who spots a horse (馬). He calls it a deer (鹿) and all but one of his advisors agree. The dissenting advisor proves that it really is a horse and the emperor executes his other sycophant advisors and raises the correct one to chief advisor.
It should be noted that it is a Japanese story, not a Chinese one. It seems to be a misinterpretation of a well-known story behind a Chinese idiom -- Point at a deer and call it a horse", which means to confound right and wrong intentionally.
Baka is also a tribe of Pygmies.
wikipedia.org dumped 2003-03-17 with terodump