In Animal Parade, if you marry the Harvest King the Sprites need to explain to him what a "smooch" is. How is this done? Colin decides to give one to Daren.
The same happens if you marry the Harvest Goddess.
Any scene with Luke in it, special mention to his and Owen's confrontation with Calvin in the ruins.
The drink off between Duke and Karen in Friends of Mineral Town, especially the aftermath with Manna berating Duke. You have to get Karen at green heart for it, but it's totally worth it.
The infamous "macaroni scene" in A New Beginning.Klaus walks into the restaurant, and out of complete nowhere, begins on a lengthy tirade on why macaroni has a hole in it and how this reflects on humanity. Clemet becomes increasingly alarmed as Klaus just keeps. Going. On.Watch it in all its glory here.
The Witch Princess' introduction in A New Beginning. She starts off by claiming that you completed a ritual to summon her—which leaves your PC very confused. She's all set to punish you for summoning her errantly... until her old nemesis, the Harvest Goddess, shows up. She's so pissed off by the Harvest Goddess meddling that she decides to live in your town solely to spite the Harvest Goddess.