The modern colloquial phrase "八竿子打不着" is used as an adjective to describe "very distant, unrelated". Example:
It literally means "couldn't hit with even eight poles". I can see how this leads to the actual meaning, but
- What does the eight represent? Eight poles (why)? A unit of measure? A metaphor for "many"?
- What does the hitting with poles signify? Does it represent a specific activity?
There are a few theories - folk etymologies really - about where this came from, but none are referenced well. The earliest record of this phrase is usually attributed to the novel 飘飞的大雪 by 母国政, which unfortunately does not shed any more light on the origin of this phrase.