Put the sugar in a warmed flameproof bowl or pan that is large enough to hold all the ingredients. Set it on a mat on the table, pour on the spirit, carefully light it and let it burn. Stir it from time to time with a long-handled spoon. It will burn for a good 5 minutes, melting the sugar and evaporating the alcohol. As the flames die down, pour on the coffee. Stir thoroughly and ladle into small coffee cups. Serve this drink immediately.