She does so by means of a reprint.
Panel 1: It's the one where he asks Mike, of all people, where Mommy keeps the spaghetti.
Panel 2: He then asks him where she keeps Lizzie's clean pants.
Panel 3: He next defensively asks why he's supposed to know where something like Lizzie's bottle is.
Panel 4: He only happens to live there, after all.
Summary: Lynn's premise is that John is too stoooopid and useless to be bothered to know where things are and what to do with them. It's too bad for her that she's presented us with an Elly who couldn't tolerate John knowing these things and actively prevents him from knowing; that kinda blunts the impact of the strip.