I find it most difficult to get along with people who get angry over a situation and then refuse to accept reasonable solutions to a problem. I would refer to them as unreasonable people.

For example, sometimes parents get angry when a child is held responsible for misbehavior. Nothing will make them happy except for their child to be “let off the hook.” I handle this by remaining calm and polite and pointing out that the school has specific rules and consequences that the student is aware of and that I cannot show favoritism to one student over another. I sometimes commiserate with the parents stating that he or she is justifiably angry, but that they are not mad at me, but with their child for misbehaving and getting into trouble.