[random] Developmental milestone...

Well, it was bound to happen sooner or later... I know, I know: it's totally normal for kids his age to experiment this way. It's probably just a phase, but it's going to be rough on the household... the best we can do is guide him without inflicting too much psychological damage. The boy has discovered knock-knock jokes. Discovered? Sort of. He's 'discovered' knock-knocks the same way Columbus 'discovered' a new route to India... He doesn't entirely understand the rules of the knock-knock joke yet, so these are quite painful. Right now we've resorted to stonewalling:

Q: Knock-knock! A: Eat your breakfast.

Send lawyers, guns and money...