As with many good stories, I don't know where I heard this, or if it even happened at all, but here goes:
Some people were playing Dungeons & Dragons, and after getting their fill of dungeons, were on a quest to slay a dragon. Like all hardy adventurers, their characters first visited the local tavern for information on their quarry. It was a white dragon, they were told, by a slobbering drunk. Slithering up there on the mountain amongst the tumbled down stones of the old imperial outpost, where brave men once watched the plain below for sign of the barbarian hordes.
Ah — an ice dragon, then. The smallest and weakest of the chromatic dragons, but deadly all the same. The adventurers, canny as they were hardy, went directly to the armorer, looking for equipment that could protect them from the dragon's icy breath. They were in luck, the armorer said: an elvish gardener had passed through not long ago, and the very same enchantments that the elf used to save her roses from overnight frosts worked just as well on plate mail. Gold was swapped for steel, and the adventurers returned to the inn satisfied, ready to sleep and restore any last hit points.
They struck out from the village early the next morning, breath rising like steam from their mouths as clambered up the shadowed hill sides. By noon they had come to the outpost, and prowled towards the heart of that forgotten place, their armor tinkling with elvish magic as they went. They found the dragon stretched out in the sun, asleep — but then somebody botched a roll, a stone clacked too loudly, and the beast awoke.
The albino red dragon reared back and spat sorcerous fire on the adventurers. The party was incinerated in an instant, cooked alive inside their armor, and as their bones smoldered, their enchanted breastplates muttered to themselves those secret words that ward against hoarfrost.
This is some semiotic judo, right here: the DM turned his players' knowledge of the game against them. Within fantasy RPGs, there are always these elemental systems, as a way of introducing some gameplay complexity to damage calculations. Instead of one number for damage, there are different types: fire and frost and poison damage. And these affinities are always signaled to the players through color palette, so consistently that the association hardly feels like one at all. The signifier and signified merge; white scales are not a sign of an ice dragon, they are an ice dragon. But this DM recognized that that's not always the case. And it doesn't feel like a cheat, because it's bringing verisimilitude into the story. It's brushing aside the artifice of the monster manual, which its dice and phony measurements, and gesturing towards reality.
That's what I take away from this story. Every sign operates inside of a semiotic system, but there is a whole system of systems, overlaid and overlapping. And the signs themselves do not speak. Only when armed with a frame of reference can we interpret them. But since we refuse to walk around without an active frame of reference, we automatically arm ourselves with whichever makes the most sense, and in that way, trick ourselves. No one in that story told a lie1: that dragon really was white.
But of course someone was deceived in the end, so we have a kind of lie of omission. It's the narrative equivalent of a poker player with an ace up his sleeve. That cheat works because even though the ace is technically a foreign object, manifested from beyond the bounds of the reality that is the particular deck of cards... it's just a real as any other ace, come off the same printing press at the Bicycle factory. Where did it came from? Oh, don't worry about that — it's on the table now, isn't it? That kind of move can get your hands broken in Las Vegas, but in fiction it's all part of the fun.
1 Unless that "slobbering drunk" was really a rival armorer, looking to get his hands on some of that enchanted armor without outright stealing it. He sends some adventurers to their doom, strolls up and collects the sooty but still serviceable items later on... sorry! I blacked out and started writing a campaign.