What to wear: You can buy a grey nun's costume, or just throw on a long-sleeved grey dress and wrap a grey scarf around your head in the same way she does. To add the finishing touches, wrap a light-coloured rope around your waist and carry around a thick book and a bell.
How to act: Strict and demoralising. Look down on anyone who's having fun and scream out, "SHAME!" at random intervals throughout the night while ringing your bell.