It is a well known Vedic fact that if you hurt ego of a person, he will never forgive you, especially, if you have insulted or implicated him in character assassination, cast implications, financial embezzlement or in public, you call a woman as old or a man as impotent.
For example, if I hurt ego of a chowkidaar, next time if a patient comes to the hospital gate and asks where Dr. KK Aggarwal is, he only has to whispery, “which Aggarwal, whose cases never survive?”
Also never hurt the ego of a person who is drunk. Under the influence of alcohol, a person loses his capacity to judge persons and situations. If you provoke him, he can be destructive and aggressive.