The simplest way to buy time while in the middle of a tense situation. Your judgement is distorted. So, pause and say nothing - calm down and reacess the situation.
Before negotiating, you want to create a favorable space. Defuse any anger, frustrations. They ,ay expect you to attack- do the opposite! Listen to them and do not argue.
You take control over the situation by moving out of the way! Buy yourself some time to think and reflect about your interests and your BATNA. Focus on what you want.