zoomerposting but iirc diary of a wimpy kid is written to be very grounded personalities-wise. the comedy in these books is derived from all of the characters being flawed in some notable ways and those flaws intersecting to create inane situations in an otherwise-realistic setting. The first book is essentially Greg’s unrelated-yet-consistent bouts of Main Character Syndrome coalescing into an incident in which to not totally fuck things up beyond repair, under duress, he has to eat a slice of moldy cheese that has been attached to the pavement for at least a decade.

there’s an element of farcicality on both sides of this where Rodrick tends to be disengaged and edgy, and Susan is overcorrecting and IIRC pretty puritanical, so it leads to this situation. It’s less aiming for commentary, more for absurdity.