Here's an example sentence: "Mathematics is wasted on him." So, trying to teach him maths is a waste of time. He'll never understand or value it. or "My cooking is wasted on you!" Meaning all the effort of me cooking was a waste, you either gobble it down without tasting it, or you won't eat it at all. You don't appreciate my cooking. The 'something' is what is wasted. What the something is wasted on is the person (or group, or other thing) that doesn't appreciate or understand the thing's value. Hope that helps! :)