An utterance is neither seen nor touched but capable of making or marring an individual, group or a nation depending on how it is used. Thus, positive utterances ensure peace and tranquility in a society while negative utterances usually tear a nation apart. Language of insult is a negative utterance that usually produces, hatred, war, or disunity in the society. This paper, therefore, investigated the language of tribal insult in the utterances of Yoruba language users. Adopting conversational Implicature and Referential Theory as a theoretical framework, the study examined the language of tribal insults in the utterances of Yoruba users of Yoruba language. Employing participatory observation and recorded utterances in informal settings with the native speakers of Yoruba, the researchers discovered that the use of language of tribal insults among the Yoruba speakers has presented some tribes less humans. Also, some words are carelessly used to insult a nation, abuser's insults are being transferred to ethnic groups with he use simile and metaphor, and negative attitude of a particular person becomes an insult to an ethnic group. The insults ranges from "theft", "promiscuity", "stinginess", "privilege abuse", "dirtiness" to "inferiority complex". The implication of the insults is that some tribes are seen as being worthiness. The study, therefore, recommends that government should put machinery in motion to check this menace in order to promote unity in diversity.