Panel 1: As our story continues, we find ourselves at the junior high school watching Principal Morton "Awkward Exposition" Bloggs (well, he has to be named something, right?) tell the students that this is the last day of class so he wants them to empty out their lockers.
Panel 2: As Mike cleans out his locker, the principal tells the students to return any library books they might have, collect their belongings and help set up an awkward joke by returning anything they don't recognize to the Lost And Found.
Panel 3: We start a two panel 'joke' about what a negligent slob Mike is when he tells Lawrence that he thinks that he found something that he doesn't recognize. When Lawrence asks what it is, Mike says that he thinks it's a lunch.
Panel 4: As Mike looks in the bag, the readership is sickened when Lawrence says that the Christmas cake still looks edible.
This tells me that Mike is the same inconsiderate and thoughtless slob at school that he is at home because the dumb son of a bitch assumes that a grinning robot will follow behind him and clean up his mess so he can bask in unearned praise forever and always like he's "supposed" to.
Summary: Oh, yuck. A horrible joke about spoiled food....and a reminder that Mike needs a spotter to breathe. THIS is the hidden subtext I had alluded to earlier when aprilp_katje had suggested I had analysed this arc to death: Mike can't even go one damned day without making a destructive ass of himself for a pants-on-head stupid reason! He doesn't even get through an afternoon without proving that he's an imbecile with impulse control problems who needs 24/7 supervision.