Dubukku is one of those slang words in Tamil world which does not have any strict meaning. To me its the clever fool in you. The you here is not really you and the clever needn't be really clever.
"I would not live forever, because we should not live forever, because if we were supposed to live forever, then we would live forever, but we cannot live forever, which is why I would not live forever." -Miss Tension Bama (correction Alabama) 1994