'Unprofessional' deemed unprofessional

Management-speak deciphering tip #1457: when somebody at work says ‘unprofessional,’ substitute ‘unusual’ or ‘threatening’. See if that helps you understand better what they really mean.

The term unprofessional is often used to characterize surprising and threatening behavior. Anything that upsets the weak manager is almost by definition unprofessional. Long hair is unprofessional if it grows out of a male head, but perfectly okay if it grows out of a female head. Posters of any kind are unprofessional. Comfortable shoes are unprofessional. Dancing around your desk when something good happens is unprofessional. Giggling and laughing is unprofessional. (It's all right to smile, but not too often.) Conversely, professional means unsurprising. You will be considered professional to the extent you look, act, and think like everyone else, a perfect drone. Of course, this perverted sense of professionalism is pathological. In a healthier organizational culture, people are thought professional to the extent they are knowledgeable and competent.
-- Tom DeMarco & Timothy Lister
Peopleware