Full moon

P-roc: "They SAY the moon is made of green cheese. That's because when you make cheese, one of the things that comes out is wane. And that's what the moon does, it wanes." Dad: "Um, I think you're confusing two different things, but that's pretty close." P-roc (who always gnashes his teeth when he's frustrated): "No, no, I'm true, that's what it is! Aarrghghgh!" (He means "whey", of course, and he's right, it's a by-product of cheese-making. That's the kind of all-important knowledge you pass on to your kid when you read the entire Little House on the Prairie series to them before they're 6.)