Although there are many authoritative studies on metaphor and impoliteness, most of them do not consider metaphor as an impoliteness strategy. Thus, this study aims to explore the different patterns of metaphorical expressions causing impoliteness in the comments sections of four fields of Korean online news articles. After collecting comments on societal, political, economic and cultural news articles based on several keywords, we categorize and evaluate the metaphorical expressions used to express impolite opinions according to the Great Chain of Being hierarchy and the features these metaphorical expressions serve to highlight and hide. The results show different patterns for different target of attack. First, conceptual metaphor HUMAN IS AN ANIMAL and its linguistic expression ‘Public is a pig and a dog’ was commonly used to highlight the baseness of the public while hiding its intelligence. Next, conceptual metaphor HUMAN IS A THING and its linguistic expression ‘Journalist is a trash’ was common in highlighting the perceived uselessness of the occupational group of journalist while hiding its journalistic efforts. Finally, conceptual metpahor HUMAN IS A THING and its linguistic expression ‘Politician with negative reviews is a dirty thing’ was often used to highlight political threats and meaninglessness while hide politicians’ efforts and humanity. These findings demonstrate the effectiveness of metaphor use in expressing impolite online and suggest new possibilities for categorization of metaphor patterns.