Public rest rooms are almost impossible to find in Mexico City. But when you got to go, you got to go. The other day, at the Mercado Medellín in the Colonia Roma, I peed here, and paid four pesos for the privilege. This is the going rate in bus stations, Chapultepec Park, markets, and the few street facilities available. I can afford four pesos, but if you earn the minimum wage in Mexico City -- fifty pesos per day -- I imagine the charge would strike you as rather steep. Memo to Mayor Ebrard: Anything you can do about this before you quit your job to rev up your presidential campaign? Remember the free-of-charge pissoirs on the streets of Paris from when you were studying public administration at the ENA? You could still keep this lady and her friend on the payroll, as attendant and assistant attendant.