Are you thirsty? If you are - try to grab a glass of water. The price is usually close to free and it may stop your hunger craving.
It may seem dull, but it can be very refreshing and satisfying. Add some ice or squeeze a lemon or lime in it and it is practically a cocktail! (not really)
I'm not sure this is really a snack. I wanted to suggest this on the site because sometimes we want to eat something because we are thirsty.
Unless you live in an area where the water is unsafe, you can just drink it from the tap. You don't need a fancy water with a fancy name to have a great water experience.