Good communication is important. As we grow older, we learn that it's usually best to be direct when we have an issue with a person or their behavior. Simply saying "Please wash the dishes, you're 35 years old" should impart a clear message that the oblivious or callous party can understand. Sometimes, however, these direct requests don't make it through to a person. Or you don't know them well enough to have an adult conversation.
That's where passive aggression comes in.
While we don't recommend taking this approach with a significant other or family member, sometimes a passive aggressive jab is what you need to a) feel better about the issue and b) get through someone's thick skull. And sometimes, these moments, notes, and signs bring amusement and levity to real problems. For everyone except for the recipient, that is.