I've always been somewhat dehydrated, which probably has something to do with my not liking the taste of water and therefore not drinking very much of it. Anyway, it turns out my mom (and probably yours) has been wrong all this time—not only do we not need to drink those eight glasses of water a day, but many people can meet the bare-minimum needs without having anything to drink during the day.
Also news to me: people who drink caffeine regularly, like coffee and sodas, become accustomed to it and don't lose fluid; a glass of Coke can provide the same amount of hydrating fluid as the equivalent amount of water! I'm still going to try to drink more water than I've historically done, but it's good to know I've not been completely parching myself all this time.
Photograph from Kid A* on Flickr