3. In a CamelBak
We know what you're thinking. The Booze Belly is a far superior invention. Wrong. The CamelBak is the better choice because it hides in plain sight. Someone letting you through security would have to think, “Man, that dude is so extreme, he's always hyrdating." Respect.
Tip: Wash it out thoroughly and as close to immediately as possible when finished, or else you won't be able to use the CamelBak for water ever again.