Coke or Pepsi, I am so thirsty, please advise!!?

I have been munching on Meow-Mix all morning and I am getting thirsty. Should I wash it down with Coca-Cola or Pepsi? I have both in the fridge, (of course they are caffeine free cos I won't drink caffeine). Or maybe milk would go better? I've noticed my cat likes milk with her food...But I am awfully thirsty and my tongue feels like it is swelling so please help me decide fast!! Thanks!