From UK Airport News
"Spending a penny" could soon become spending a £ or Euro...Well that's inflation for you! No doubt the crew will have to pay as well......
Next refinement will no doubt be a charge per litre or kilo dependant on whether it is "number ones" or "twos" 
And here's an opportunity for airport shops to stock incontinence pads for those blokes who can't tie a knot in it or ladies who can't keep their legs crossed 
Suzeman
17.01.10
Ryanair will press ahead with plans to charge passengers to use its aircraft’s toilets, the Irish Times reports. Despite admitting an announcement last year that it would install coin-operated facilities was a publicity stunt, chief executive Michael O’Leary is now revisiting the issue, according to the airline.
The budget airline would remove the two toilets at the back of each aircraft, leaving only one on board and creating room for six extra seats. The fee would mean there there is less demand for the limited facilities on board, but things could get difficult if the only toilet broke, which could mean that aviation authorities would not accept the plan.
In its in-flight magazine Ryanair described the coin-operated toilets as a 'cost saving proposal' that would help reduce fares by at least 5 percent. Spokesman Stephen McNamara told the newspaper that the €1/£1 charge would apply only to flights of an hour or less, which would include almost all Ryanair routes between Ireland and Britain.