Panel 1: We start things off on a very early morning at the Patterson house with Liz in her housecoat getting ready for the day by washing up and brushing her teeth.
Panel 2: She squeezes toothpaste onto her toothbrush.
Panel 3: We find ourselves looking at Mike's ugly, stupid face smiling a mean-spirited smile because Elizabeth gurgles in discomfort owing to the presence of something on her toothbrush that's caused bubbles to come out of her mouth.
Panel 4: We do a tight zoom on Liz's face as she unhinges her jaw and yells to Elly because Mike put soap on her toothbrush.
Panel 5: He stands there making the who-me gesture when Elly delivers some sort of lecture that doesn't penetrate his thick skull.
Panel 6: Having imposed a toothless non-punishment of some sort, Elly's silhouette vanishes. Since he knows his mother too damned well, Mike laughs at Liz's expense because he got away with punishing her for asking to be born and stealing attention away from his selfish, worthless ass.
Panel 7: As Mike brushes his teeth, Liz comes up to him and says "Guess what?"
Panel 8: When she says that she used his toothbrush, he asks "Yeah....so what?" because he can't see her as someone who can or should fight back.
Panel 9: Since he's stupid on top of being bad, he doesn't understand what she means when she says that she didn't use it on her own mouth.
Panel 10: When she points to Farley and tells him that she used in on the dog, Mike goes all gobsmacked.
Summary: The problem is not just that rolling around in the mud too is no way to get clean. The problem is that nothing can ever teach Mike "Liz didn't ask to be born either so my behaving as if she's an interloper who has to be chased away so I can be loved again means that I am the selfish and imbecilic loser brat kid people call me when they think I can't hear them."