I'm sure these are all valid too
  1. He's allergic to it
    If this is the case you're in big trouble bud.
  2. It's too clear
    You WANT water to be clear kiddo.
  3. It's in a pink cup
    Apparently water can only be drunk from a YELLOW cup.
  4. It doesn't taste like pink lemonade
    Your right, because it water, not pink lemonade.
  5. It's too wet
    I give up. I suppose you'll just die of thirst. I'll miss you.