Hermione tilted her head; what would be a good word? This was tricky; a word she could remember, but wasn't prone to using. "It can't be obvious...or something people who come over use, unless they were an intruder..." She sighed and started tapping her fingers. "This may sound odd, but what about something like...mudblood? Or a similar term?" She continued without pausing. "I know you don't like it, but logically it works. The only people who would use it are people I don't want here. And there's no chance I'd mistakenly say it."