When you know you committed a fault and the opposition is now trying to catch hold of you and beat. You will obviously be afraid seeing them. Your legs starts shaking and heart beat increases.
But you hide all those inside yourself and make sure the other person does not notice it. Because it is a human tendency to frighten a person much more when he is already frightening. So hide it inside yourself and remain silent.
You observe that they even make some wrong alleges on you and at that time too, make sure you utter nothing and remain in complete silence. Because at that point of time, generally people will expect you to speak, but when they realized that you are silent, they will doubt your silence, starts thinking in all the possible angles and finally will be left with no option or any answer as to why you are silent which puts them in complete confusion.
At this situation, they even avoid to take any severe action on you as they doubt that your background might be big.