Okay, maybe something of a CIDU-LOL. Google Translate is not as helpful as one would like — I don’t trust “cable castanets” . I do rather trust “box castanets” but why “light box castanets”? That’s not a “light box” as used in graphics arts, anyway. And I think the primary joke is our stand-in character enjoying “vulgar castanets” instead of “common-or-garden castanets”.
Is her expression already reacting to this irritating oversight?
But maybe this one was meant to make up for that?