If anyone's interested, the full story of ra'taj and raktajino, as Christopher summarized, is the following:
Klingons have developed a way to make coffee particularly strong, both in flavour and in its effect as a stimulant, and it’s a very popular beverage. As a rule, coffee is consumed plain - that is, black - but some Klingons prefer to mix other ingredients in with the coffee. If some kind of liquor is added to the coffee, the drink is called ra’taj. It’s said that the drink was originally nicknamed ra’wI’ taj (“commander’s knife,” suggestive of its potency), and that the name was shortened over time. In any event, ra’taj became one of the few Klingon foods to gain popularity outside the Empire, though in an altered form. Instead of containing liquor, as does the genuine Klingon ra’taj, the “export” version (which came to be pronounced <raktaj> in Federation Standard) consists of strong Klingon coffee plus a nutlike flavouring. Eventually, a new fashion developed - adding cream to the <raktaj> - and with this innovation came yet another name, <raktajino>, modelled after the name of another popular coffee drink, cappuccino. Raktajino is now served hot or iced, with or without extra cream, and with or without the rind of some fruit to add even more flavour. Though it’s sometimes called “Klingon coffee,” it’s quite different from both plain coffee and the alcoholic ra’taj.
So there we are.
