Glass Half full?

I sometimes hear the question, "Is the glass half full, or half empty?"
Its a trick. Don't fall for it.
To answer the question as asked is to answer an incomplete question. We must think outside of the box, an artificial box defined to trick us into an answer that we may not like the result of.
The real answer is that the glass is completely full, not with water necessarily, but half full of water, half full of air, or at least half full of water and half full of water vapor, since if we suck out the air, the water would sublimate and fill the remainder of the glass. There could be very few liquids in the glass for which this would not occur, vacuum oil or mercury might be a couple of them, but usually the questioner isn't that clever, and is counting on the questioned to not be so clever.
So answer this question in the correct manner and be judged either as an outside the box thinker, or as very clever. Answer that it is an incomplete question, the answers are not complete, or simply answer "completely full," let them chew on your answer and win a game that you likely didn't want to play in the first place.