This is what occurs when your overbearing, micro-managing boss is not in the office for the day and you finally have a chance to relax and enjoy your day and co-workers. Usually, little or no actual work is accomplished during this time, so you are on a kind of vacation even though you are at work.
Jim, why is everyone smiling and laughing over here today? What happened?
Nothing. We're all just on a workstation vacation because Janet is out for the day at a conference.