At first glance, the purple scrawls might seem like useless graffiti...but look closely - it's an argument:
A written dialogue between the kids! How clever! IN PURPLE MARKER ON MY WALL, which completely voids any hope of my praising their cleverness. Questioning reveals that neither boy had anything at all to do with the writing on the wall. Nothing! Not one thing! Punishments were still handed out, because we're just mean that way. And no, in case you were also wondering, they may not help repaint the wall.