It's a delicate art form, really. A subtle dance of subtle hints and not-quite-so-subtle jabs. You know, a well-placed sigh, a raised eyebrow, a "Oh, I'm fine, really." The key is to convey a message without really saying it. To imply without ever directly stating.
Take, for example, the art of leaving a passive-aggressive note on someone's fridge. A simple piece of paper, a few strategically chosen words, and voilà! The message is conveyed without ever having to actually speak the words themselves.
Of course, it's all about the subtlety. You don't want to come across as too obvious, too heavy-handed. No, no, no. That would be too... aggressive. You want to be like a gentle breeze on a summer's day, a whisper in the ear, a subtle suggestion that "Oh, maybe you could, you know, clean the sink?"
Next: Chapter 4, The Agony of Actually Caring