As most of you already know, in Spanish, the English word 'juice' translates as jugo and 'water' translates as agua. But what these two words can represent in their respective languages is not exactly the same. In the U.S., any sort of fruit or fruit-flavored beverage can be called 'juice,' even if it doesn't actually contain any real fruit juice.
In Mexico, jugo means 100% fruit pulp and 100% fruit pulp only. So if you go to a restaurant or juice bar and ask for a jugo de naranja, you're going to get pure, fresh-squeezed orange juice. And you're going to get a good deal, too: a big, 16-ounce size glass for a buck or so. Fruit pulp or juice concentrate added to water, on the other hand, is called agua. So the kind of thing that often passes for 'orange juice' in the States would be called agua de naranja here. It makes sense, huh? I tell you, fresh jugo is one of the things I appreciate most about living here, not to mention all the fresh fruits in general that are so hard to get in the southwestern U.S.
How much does the fresh juice cost? It usually will run you about 7 pesos for about two cups of fresh squeezed juice. One of my old students, named Vladimir, has a taco stand where he makes fresh orange juice for his father, who owns the joint. Good tacos and good juice during my break also helped the day go faster.