This document outlines 10 things you should never say to your boss. These include saying "no," "I cannot," or "I don't know" as it shows a lack of willingness. One should also avoid saying "I'm sorry, but..." or "that is impossible" as it comes across as negative. Additionally, one should not threaten to leave, ask to leave early without good reason, compare the current boss to a former one, say something is not part of your job, or blame others. The key is to think carefully about what you say to avoid damaging your career.