(Original Publication Date, 12 April 1991)
Panel 1: As Mike types up a report on his computer, he comes an oh-so-typical conclusion about the name April when he asks Liz if she knows what she's going to be called when he half-way anticipates Jeremy Jones and says that she's going to get called "Ape". All he's missing is "the Grape."
Panel 2: He makes a nasty comment about how his two sisters are "Ape" and "Lizard Breath" before becoming Call-Back Boy and saying "Dizzy, fizzy, busy Lizzie." Since Lynn probably forgot the strip for 6 September 1986, she probably thinks that the Delicate Genius (and not a boy named Patrick) was the first person to notice this. Given how Liz unhinges her jaw and yells "CUT THAT OUT!!", so does she.
Panel 3: As Elly nurses the baby, Liz comes up to her and tells her that it's no fair that Mike can call her and April names and she can't call him anything. Since she's Elly and thinks that children fight as a matter of course, she asks "Why not?" because she doesn't know that Mike's rhyming is setting up the punchline.
Panel 4: Elly is gobsmacked when Liz says "Because nothing rhymes with Michael." Well she should be because Liz lacks the imagination to realize that what Mike is doing isn't actually rhyming when he shortens April.
Summary: Liz eventually comes to realize that the smug rat is vain on top of being a peevish lout who thinks that seeing other people as being real means that he is diminished. Thus he becomes Ugly Brother.