"Psychology. Purebloods and Death Eaters won’t notice or care about Muggle culture. In fact, the higher up they are in You-Know-Who’s army, the less they’ll know. It’s a point of pride for them." She smiled grimly. "If I use a name with a coded Muggle reference, then Pureblood enemies will overlook it and Muggleborn or halfblood friends might recognize it. Most Muggleborns older than me in the UK would recognize a message to or from "Belle O. St. Trinian.’ And they know it means trouble."