When my son was three years-old, he had an astonishingly straightforward way of expressing himself. If he was busy doing something and we told him it was time to do something else (go to bed, get in the car, take a bath, whatever), he would just look at us, incredulous, and say, "But I want to do what I want to do."
Sometimes he would repeat it. Slowly. Because we didn't seem to understand the perfect logic, as if to say: "How are you people not getting this? Are you that dense?!"