The trick is to look the barman in the eye and give a short, emphatic nod as you order a Coke. Discreetly, the rum tumbles in and, discreetly, you toast the barman, your accomplice in crime. The Venezuelan president, Hugo Chavez, has banned alcohol in the week leading up to Easter Day to try to cut the number of drink-driving-related accidents, which soar during the holiday exodus for the beach. For Venezuelans, by some measures Latin America’s biggest boozers, the edict …