Panel 1: We zip ahead to find Mike and Lawrence at the back porch of the Pattermanse. I'd say that since school usually lets out at noon hour on the last day of class, it's pretty much one in the afternoon when we find Mike sourpussing about the fact that Elly's at work and like a nitwit, he forgot his house key or lost it or something.
A sane person would use the doorbell and, if someone is there, ask politely to be let in and go elsewhere if there is not. Since this is Mike, we know what's going to happen.
Panel 2: What happens is the first use of the demeaning nickname "Lizardbreath" as Mike turns into a foaming at the mouth lunatic pounding at the door in blind rage one second after he realizes that he locked himself out whilst yelling "ELIZABUTT!! ARE YOU THERE? HEY, SISTWERP! E-LIZARDBREATH! HEY, DWEEB! OPEN THE STOOPID DOOR!!!"
Panel 3: When Lawrence suggests that perhaps she isn't at home at all, pissed-off jerk Mike unhinges his jaws and yells OH, SHE'S THERE ALL RIGHT! HEY, DOORKNOB!! CAN YOU HEAR ME?!!!
Panel 4: She does something Mike refers to as cruelly provoking him by saying that she can hear him but she is not listening.
Summary: This is the pants-on-head stupid means by which Mike waltzes blindly into trouble he doesn't need: the second he gets frustrated, he turns into a raging asshole with an allergy to being considerate of other people. This is the end result of Elly's insistent need to declare any emotion that might require her to get off her ass and parent fraudulent and her active refusal to care about whatever 'meaningless' thing that the kids 'know' isn't worth worrying about: siblings who will war against one another long after her ashes have cooled.