The phrase "son of a bitch" is an insult used to describe someone who is considered to be unpleasant, disrespectful or deserving of criticism. It is often used as a way to express anger or frustration towards someone who has done something wrong, or is behaving in a way that is considered to be unfair or unjust. The phrase is derived from the fact that it was once considered a vulgar way to refer to someone's father, and is therefore considered a very strong insult.