The greeting given to co-workers who pass by in a hallway at work.
Hallutations invariably progress from a friendly "
good morning" or "hey" at the first encounter of the day with a given co-worker, to a quick nod of the head, then to the subtle 'eyebrow nod', and finally to an aggressive refusal to acknowledge the co-worker's
existence for any more passings.
At the end of the day, this progression resets, and the next morning hallutations are again initiated in the friendly "hey" stage.