And the latest issue of Medievalist has a costume idea:
A Plague Victim.
It’s easy costume to prepare: – use beet juice rubbed on your face to create a flushed look. Buboes can easily be made from bread dough – use honey to attach to your underarms. Wear an old dress or other clothing you don’t mind getting dirty – this way you can fall to the floor groaning dramatically. You can take advantage of the conflicting theories about the black death and, when caught eating, claim an enormous appetite is a common symptom. You can throw your ‘buboes ’ at people, both delighting them at your humour and disgusting them at the same time!
Edited to add: I’d have a blast with that – I’d probably go with ready to bake biscuit dough, paint the outside with food colouring, then make a hole to pour in slightly whipped cream, tinted green and yellow with food colouring, then pinched mostly closed. If you threw one of those at someone, you could properly make them scream! :D