So a negotiation is a business discussion that occurs between two  adults, correct? 

Well, in a lot of cases this is a correct statement.  However, there are times when things can become heated during a  negotiation. When one side feels as though they are not getting their way, they start to look for ways that they can convince you to change your mind. One  tool that they have available to them besides using different  negotiation styles and negotiating techniques is to threaten you. 

If they decide to do this, how should you react?