Chocolate milk and "aguas frescas" (fresh waters).
I don't know what it is about Mexico/Latin America or the rest of the world, but we just love our fresh waters here and they don't seem to be all that common in the rest of the world. While some cultures might have something similar, the preparation/presentation is different.
They are served cold or chilled and made from the natural and fresh ingredient that gives the water it's name/flavor.
Yeah, you can buy a liter of concentrate at the supermarket and make gallons of that stuff... but it's mostly artificial flavoring, coloring and taste- just not as refreshing.
It's not juice. Lemme explain.
Jugo de Naranja/Orange Juice - you squeeze tons of oranges and drink that. No added sugar, water... pure juice.
Agua de Naranja/Orange water - squeeze one orange into a glass of water, add a bit of sugar. Similar to orangeade if you've ever traveled in the southern US states... but not quite. See next point.
Naranjada/Orangeade - Words are direct-literal translation and the beverage is the same. It tends to be sweeter and uses more oranges than orange water but less than orange juice.
Most common ones here are:
Agua de limon (lemon water) - somewhere between the Italian limonatta and American lemonade... yes, the words are the same (translation wise) but the beverage isn't. Anybody with a half a taste bud could notice.
Agua de jamaica (hibiscus water) - similar to hibiscus tea, one is more tangy and the other smooth (besides one being prepared in tea form and the other one being prepared in extract form).
Agua de horchata (rice water) - Very milky, very sweet. Usually served with cinammon. Similar to drinks found in south east Asia.
Agua de tamarindo (tamarind water) - Again, similar to some south east Asian beverages. Spicy and sweet.
And just about any fruit we can get our hands on (watermelons, strawberries, mango).
In high pedetrian traffic places (parks, outside of malls, office clusters, near subway stations, etc) there will be juice stands, where you can get a freshly made juice or water from your fruit of choice (or mix 'em up!).
I really miss 'em when I'm out of country... seems that everywhere you can just find soda, tea/coffee and store bought juice from concentrate (Bear Naked? What an over-priced gyp). Yeah, we got 7-11s where we can buy that stuff too... but I'll take a chilled and freshly made hibiscus water over a soda any day. It hits the spot just right.