A Twenty-Highlighter Girl is usually a girl named Zoey who gets As and takes a gagillion notes. Usually, a Twenty Highlughter girl is a bitch who snitches on John when he tries taking Mrs. Thompson's spot as a teacher and then won't allow Andrew into Class because she's so special;
Dave: Did you hear about how Zoe is a Twenty Highlighter Girl
Jym: yeah I heard she snitched on John and wouldn't allow Andrew into the Class