A person may ask explicitly about one matter while the practical need behind the question concerns something else. In such cases the answer may appropriately address the underlying purpose rather than the wording alone.
إِخْرَاجُ الْكَلَامِ عَلَى خِلَافِ مُقْتَضَى الظَّاهِرِ
Expressing speech differently from its apparent expectation for an intelligible purpose.
This kind of redirection is meaningful only because it still answers something relevant to the original inquiry. An unrelated answer would not acquire rhetorical merit merely by being surprising.