Today's strip has nothing to do with Halloween and everything to do with making Rod look like an oaf; that's because it's the Smutty Book strip.
Panel 1: John asks a smiling Elly if the book he's holding and the ones she's stacking together are the required reading for her night school class.
Panel 2: Having not actually been answered, he asks if she's sure if this is a course in Contemporary English.
Panel 3: Having forgotten she's taken Creative Writing, Elly says "Sure it is" and asks him why he's asking.
Panel 4: He looks down at the page and declares that there isn't a smutty book in the lot.
Summary: Since John is a bit of a prude when he wants to be, it's obvious that he mistakenly believes that all that modernity means is that people are more frank about you-know-double-you-aitch-ay-tee. That, or he's yanking her chain to get his kicks again.