Answer:
I once was very frustated while trying to explain something I saw. My father has a very good friend who came to visit with his family. His son behaved impecably when the others were around, but was mean to us as soon as they left. He would act as if he owned our home and tried to boss us around.
One day he ended breaking a few dishes and blaming it on my little brother. I tried to tell my parents it was a lie, that he was the one who had broken them, but they wouldn't listen. They even accused me of being a liar. When I began to scream in frustration, it only go worse.
Later on, when the guests had already left, I decided to talk to my parents. I began by saying that there were three people who really knew the truth: myself, my brother, and the other boy. I told them there was no way for them to know the truth themselves, since they weren't there to see what had happened. They would have to choose in whom they would believe and I hoped, I said, that they would choose to believe in my brother and I, since they'd raised us and knew our characters well. They listened, finally.
Changing from an agressive tone to a calm and sure one helped me get my message across.
