Perhaps it's meant to prove that Mike needs a lot of help looking good; that's because John is doing actual parenting.
Panel 1: We see Mike in his jammies playing with what Lynn refers to as 'one of those toys that does everything' and what regular people call a handheld video game. John tells him light out and Mike whines "AWWWH?"
Panel 2: As he motions for Mike to hand over the PSP, John reminds him that he has school tomorrow and is grouchy when he's tired.
Panel 3: John says "Lights out" and turns out the light.
Panel 4: As we see Mike under the sheets playing with the game using a flashlight to see, John tells him to not do that.
Panel 5: As we see a testy John about to ask him to hand over both the flashlight and gaming system to be handed back to him after school tomorrow, Mike, who doesn't yet realize that blankets aren't very good at blocking light, asks how they always know.
Summary: John is being a fairly responsible parent here; he just has to work on not acting like Mister King Discipline Man and forcing compliance to his demands. If he keeps crap like this up, he'll end up making a huge, ugly fool of himself.
ETA: The latest banner makes a nonsense of John's argument.