Here is my new favorite thing: I love it when you’re walking down a hallway, say, at work, and you see someone you know slightly, but not all that well, and they give you the half-smile. You know the half-smile. It’s the one where you eat your lips and keep your teeth well-covered. If you have dimples, those might appear, briefly, but otherwise it just looks like you’re having a seizure.
The point of the half-smile is to indicate to the person you’re half-smiling at that you are interested in being courteous, but not necessarily all that invested in the other person’s good opinion. You’re going for friendly, but not needy.
This has replaced the “Whassup!” chin nod as my favorite office-appropriate greeting.