Ad Hominem happens when the argument is aimed at the person not on the reasoning. I have my examples of ad hominem fallacies which have been used in the few past events. I had one of my friends in the class who was very calm and quite. He never got into fighting; or rather he was not given much importance on that. Once in an event he was asked by the teacher to present his opinion; I was the first person who commented on him that he did not know how to speak. In short, I called him dumb.