Just Plain Nasty is an expression used to describe something that is particularly unpleasant or offensive. It is often used to describe a person's behavior or attitude, but can also be used to describe a situation or experience. The term is derived from the phrase 'just plain nasty, ' which was first used in the early 1900s. The crossword solutions for the term Just Plain Nasty are MEAN, which is an adjective meaning unkind, cruel, or spiteful.