For anyone who knew the old Soviet Union, a visit to Cuba is always a trip down memory lane. From the ubiquitous revolutionary slogans and the absence of advertising, to the cautious shorthand in conversation (stroking the chin means Fidel Castro) and the sour, fatalistic jokes, it is a Communist country of the classic era. But this time, I kept thinking about an old Soviet joke that had not made it to Cuba (though I have now done my best to get it started there).