Oh anne--this is almost a YART. Tsuwm had boondocks in his list of favorite new words--i think it was one of the first threads i responded too-- Tsuwm credited the US Marines for introducing it to English-- (and i had heard the same) but the marines got it from Tagalog--

as for how it got into japanese-- (well those marine where in the boondocks fighting with someone....) it works as a japanese word, since the japanese tend to like constantant/ vowel combinations-- they have trouble with words like strawberry-- and the word they use is satarawaberi-- they just shove vowels in to the S T R blend-- but boon dok "works" in japanese. I never knew it was also used in Japan-- the only other word i know in English from Tagalog is Yo-yo.