(Strip Number 4570, Original Publication Date, 25 February 1986)
Panel 1: As he and Elly get ready for bed, John tells her that Mike finally understands percentages and fractions now.
Panel 2: He then complains about how he had to go over and over the same material again and again.
Panel 3: He then starts to hang his shirt on the mirror like a damned farmer. As he does so, Elly makes a faint, irrelevant buzzing noise that almost sounds like "Honey....could you NOT hang your shirt on the mirror? It drives me crazy!"
Panel 4: As he walks off having not heard what she said because he doesn't want to, he marvels about how funny it is that you can tell someone something a million times and it just doesn't sink in.
Summary: I should think that the moral is that a person actively has to want to hear something for something to be heard. Well, that and the fact that John simply doesn't seem all that concerned with what drives Elly crazy.