It's exactly what I thought it was.
Panel 1: As could have been expected, enforced togetherness and Mike's envy have soured his and Lawrence's moods; Lawrence's "NERD!!" is answered by "Creep!!" We follow that by "I hate your house! Then go home! I can't wait!"
Panel 2: Elly shows up and says "Okay! Okay! Break it up, you two" as she separates the combatants.
Panel 3: As she and Barnacle Lizzie leave, she tells them to hang on just one more day; that's because Lawrence is going home tomorrow.
Panel 4: The two of them get all sad-faced and yell "Already?"
Summary: This is, of course, because while they're not getting along right now, Mike and Lawrence don't want things to get back to normal. Mike likes having to choose who he can play with and Lawrence likes having a different inattentive parent pretending to watch over him.