The head of Ryanair insists that he's serious about making passengers pay for the right to use onboard bathrooms.
Michael O'Leary says it's something that eventually will happen. But he told reporters in Dublin today that there just isn't the mechanism in place yet for charging bathroom users.
He says he's asked engineers at Boeing to design toilets with doors that open only if you swipe a valid credit card through the locking mechanism.
O'Leary says his earlier idea to make them coin-operated wouldn't work, partly because the airline operates in areas using both the euro and the British pound.
He says most people would simply visit the bathrooms in the airports before they get on board, or wait until after they land.
But he says those who have to go, and who are willing to pay for it, could provide more than US$20 million (A$31 million) in additional annual revenue to the airline.
When he first floated the idea, aviation analysts weren't sure if O'Leary was kidding -- perhaps poking fun at his own entertainingly bombastic reputation.