"ha" = wave "dou" = motion "ken" = punch.
who the hell knows, it's probably the misheard taunt that japanime kickboxing/martial arts games use, obvious only by the fact that blue flame that emits from fists after executing a bitchin combo 17x in a row wins the round, and makes you l33t.
or, it's something even lamer.
it's HA DOO KEN mutha fucka
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