How to get your housemate to do washing up?

With the hard heads, you have to be blunt. There's no other way around it because they are hard heads who call your bluff. You could try putting some signs up around the house. You could use something catchy like: 'If you don't do the tow, ... you'll have to go.' Or: Look ladies, we're all grown women living here, and your mamas are not around to clean up after you dear'. Or you could just go plain and simple and write: 'CLEAN UP AFTER YOURSELVES!' lol. And keep a record of who is doing their part and who isn't. Like if Jane was the last one to come home to a clean kitchen and house, and you find a dirty cup and plate in the sink later on in the evening , you'll know that it was Jane who was the culprit. Good luck anyway, but don't ever be afraid to boot unclean people. Hold your ground.