Actually, we have him outwitting the holy living crap out of his petulant moron of a son.
Panel 1: It's late in the day and John tells Mike to put his pajamas on; Mike declares that he wants to sleep in his clothes.
Panel 2: John repeats his request; Mike refuses on the grounds that his way would mean he wouldn't have to get dressed in the morning.
Panel 3: John hands them over and says to put them on; Mike says NO!! and asks John to give him one good reason.
Panel 4: John points out that there isn't actually a good reason. The world wouldn't end if he slept in his clothes. Granted, he'd be hot, uncomfrtable, would itch like mad
Panel 5: This causes Mike, who's being depicted as being contrary-minded for its own sake, to want to wear his pajamas now.
Summary: I don't see why Lynn's so hepped up to have grandchildren; we just know she's going to misinterpret their behavior too. Despite what we see here, children usually have a reason for being defiant.