Adjective. Used as a pejorative to describe a place or thing (as well as infrequently used to describe a person or persons) as being overtly white trash/hillbilly/redneck/Appalachian. It also thereby implies these places have qualities that are ascribed to the aforementioned adjectives, such as racist/white supremacist, incestuous, impoverished, poorly educated, politically right-wing, and fundamentalist Christian. It is a secondary adjective for the respective word which is ordinarily used to describe a particular sound attributed to music such as bluegrass, specifically referencing the desired sound of the string instruments such as a banjo.
When we went down south for Aunt Ellie May's funeral, I decided the place was too twangy for me to bring my boyfriend or be seen as an interracial gay couple, so I told him not to come and put on my best jeans, shirt and camo hat.