Heh, that's something that happens in the Kingdom of Loathing too, though it doesn't impact any built-in gameplay.
There are third party sites that get a feed of all in-game transactions, and track whether prices are rising or falling on items. Of course, this can be manipulated in exactly the same way described in the OP -- either for humorous reasons, or for some sort of trade scam.
Though KoL's economy is in general really fascinating. And it interacts in neat ways with the way they make money. They were way ahead of the curve in using a sort of free-to-play model. (And even doing it in a way that doesn't feel scummy!)
There are third party sites that get a feed of all in-game transactions, and track whether prices are rising or falling on items. Of course, this can be manipulated in exactly the same way described in the OP -- either for humorous reasons, or for some sort of trade scam.