Glee follows the fortunes of a school’s Glee club as a teacher, Will Schuester (Matthew Morrison), attempts to revive the club to its former glory and, as the episode starts, he has accompanied one member of the club, Tina (Jenna Ushkowitz), to see the school’s principle Figgins (Iqbal Theba).
He confirms she is in trouble for her goth attire and has tied the look in with vampirism and, from there, Twilight. Scenes, from another school, of high school girls wearing capes and fangs and attacking a geek, in order that they might attract Robert Pattinson’s attention, appear. It becomes apparent that Figgins believes in vampires. Transforming into a bat is mentioned. She must change attire or be suspended.
|Tina as a vampire|
So a fleeting visitation, but there nonetheless. The episode's imdb page is here.