Worker's Gasp
The Worker's Gasp is used at work when two employees who usually don't know each that other well cross paths and do not know what to say to one another. Instead of trying to come up with quick small talk, one or both employees will instead simply roll their eyes and let out a gasp when they cross paths and make eye contact. This is used much like a simple nod is, but unlike a nod, this gives opportunity for mutual agreement without any spoken words - the mutual agreement being that work sucks and you both don't want to be there, hence the rolled eyes and gasp.
When I first started working and didn't know anyone, I would always let out a Worker's Gasp to all my co-workers that I crossed paths with.