(Strip Number 723, Original Publication Date, 10 October 1984)
Panel 1: Elizabeth teases Michael that she is the favorite child.
Panel 2: Mike and Lizzie trade a do-not-do-so before a hacked-off Michael asks her how she'd know.
Panel 3: Lizzie explains that Mommy and Daddy gots a boy an'a girl. Mike asks her to clarify her logic.
Panel 4: She does so by saying that if they'd liked the boy the most, they'd have had another one.
Summary: The problem with Lizzie's logic is that John and Elly really don't start liking their children until they're old enough (and beaten down enough by life) to start handing their poooooooooor, martyred parents undeserved goodies. Since Mike can provide more children named Patterson, he's loved the best after all.