O'Leary said they will start charging 1 pound for using the toilet.
Without getting into the specifics, under EU law if someone is selling food and drink in a premises (here an aircraft) with more than X seats and/or more than N square meters, they are required to provide toilets free of charge. Thousands of businesses across Europe do not respect this law (many eateries in shopping centres provide shared toilet facilities that you need to pay for - ILLEGAL). This law is not being enforced to any significant degree. But surely the EU would challenge a massive entity like Ryanair if their were to ignore this law.
I suppose, as a work around, by buying something to eat/drink on a Ryanair flight you could receive a token for free use of the toilet, where other passengers would need to pay.