It’s a great clip to use for exploring how meaning is socially constructed. From Harry Potter and the Chamber of Secrets, Malfoy angrily calls Hermione a “mudblood,” causing Ron to (attempt to) cast a spell on Malfoy. The spell backfires; Ron ends us spitting up slugs. When the trio–Harry, Hermione, and Ron–visit Hagrid for help to deal with the slugs spell, Hagrid asks why Ron was trying to curse Malfoy. Harry responds confusedly.
Hagrid: Who was Ron trying to curse anyway?
Harry: Malfoy. He called Hermione…um, well I don’t know exactly what it means.
Hermione: He called me a mudblood.
Hagrid: Huh?! He did not.
Harry: What’s a mudblood?
Hermione: It means ‘dirty blood.’ It’s a really foul name for someone who is muggle-born, someone with no magic parents, someone like me.
Harry doesn’t know what mudblood means. Everyone else in the scene does. Others know what it means because they have been exposed socially to its use and meaning. That’s what causes Ron to respond so quickly to Malfoy’s use of the epithet. But because Harry has never heard of it, all he knows is that it is probably a rude word but that’s all.
Language works this way all the time. And when working with students (or really in any social situation), it’s important to attend to the fact that some of the words, phrases, acronyms, and references one makes might in fact be sociolinguistically new to others. The result won’t be slug vomit, but it could well be worse: you’ll make others think they can’t participate and learn.