Is there one overarching rule, or does it change from card room to card room, where you can tell players (either heads up or multiway) what your hand is. I would imagine that because it is so easy and accepted that one lies at the poker table, if we can say what we don’t have and lie about it, is there any reason why we couldn’t tell people our exact hand.

I’d imagine there’s no rule against this because someone could just state any two cards, but does this change if it is, say, preflop and there are still players to act?