[Magic_Man]

I totally respect your desire to undermine stupid school rules with technicalities. We need to think about what they will be asking, verbatim. Is it going to be "What's in your cup?"? In that case, I agree you can say "My cup contains water" without lying, but I think it will be quite obvious that you're being a smartass. However, you're also likely to be faced with "You know that you're only allowed to have water, right?" in which case you can truthfully answer "yes," and if they follow up "Is that water in there?" you can fairly truthfully answer "yes." I'm still debating on that last one.

~MagicMan