What's Your Poison?

I used to drink diet coke or diet pepsi during my tournaments just because I like the taste and don't really care for water (go ahead and laugh, I don't mind). But a few years ago, a friend told me their coach told them caffeine can affect your play, so he suggested to her to not drink a lot of caffeinated drinks during a tournament. So, I switched to only drinking water during my matches at tournaments. I cannot drink alcohol and play well, so that was never an option and I don't like coffee. I have found I actually cannot play in a tournament without water now. It's kinda freaky!

So I was curious, what is your poison? What do you normally drink during your tournaments?