There are several synonyms for the phrase "ill-bred fellow." One such synonym is "boorish person," which implies a lack of refinement or manners. Another synonym is "uncivilized individual," which suggests a lack of socialization or culture. A third option is "ignorant person," which implies a lack of education or knowledge. A fourth synonym is "rude person," which denotes a lack of consideration or politeness. Ultimately, all of these terms describe someone who behaves in a manner that is deemed inappropriate or unsavory by society. However, it's important to remember that it's not productive to judge or label individuals solely based on their behavior and upbringing.