"Plug ugly" is a derogatory term that refers to someone who is unattractive or unpleasant in appearance or behavior. There are several other synonyms for this term that can be used in different situations. For example, "ugly as sin" and "fugly" are common alternatives to "plug ugly." Another term that is sometimes used in place of "plug ugly" is "homely," which suggests a lack of physical beauty but not necessarily unpleasant behavior. Other options include "unsightly," "repulsive," "hideous," and "grotesque." While it's important to avoid using derogatory language, understanding the nuances of different synonyms can help you communicate more effectively in a range of situations.