Dumbledore is giving a speech and you walk in not wearing your uniform but a black dress everyone turns to look at you

Ron:"who is she??" Hermione:"that's my sister!" Fred and George:hoo~" Harry:"does she have a boyfriend?" Draco:"she's my girlfriend stupid pottah!" Cedric:"don't you think I'm better then Malfoy?" Hermione:"where is your uniform??"