A water bottle that is emptied and instead filled with Vodka or other substance that looks like water. Common when going to a public location like a park, baseball game, or even class.
Man1: "Dude why do you cringe everytime you take a sip of your Arrowhead water?"
Man2: "It's my secret water man."
Man2: (in a whisper) "My Skyy water..."
Man2: "It's freaking vodka you nut."
Man1: "haha niceeee."