牛头不对马嘴: horses jaws don't match cows' heads -- incongruous.; as incongruous as the mouth of a horse on the head of an ox; irrelevant; things that don't agree
不相干: be irrelevant;have nothing to do with; [数; 光] incoherent 短语和例子不相干的话 irrelevant remarks; 完全不相干 altogether irrelevant; 这与你不相干。 this has nothing to do with you