I once had a minor medical procedure done in Mexico. The doc wanted to be paid in cash, and I obliged. Then I asked for a receipt. What followed was Keystone Cops. It took a while for me to realize I was being stupid. By asking for a receipt in the double economy of Mexico I was asking the doc to sign a confession to the tax police. He was right, I was wrong, and I learned something about the underground economy in socialized medicine. Welcome to Mexico, friends, where the people are warm and wonderful, the drug gangs ruthless...