Peter N-H of the <a href="http://members.shaw.ca/pnhpublic/China.html">Oriental List</a> quotes a thread--that I can't find--on the <a href="http://thorntree.lonelyplanet.com/">Lonely Planet Thorn Tree</a>  about a new scam recently spotted on <q>a bus to Anxi</q>:

<quote>Afterwards, and after a bit more shouting, the dodgy looking bloke pulls out a further wad of this foreign currency - which he apparently snaffled from the wallet - and everyone goes berserk, people are handing over RMB left right and centre, and we hear the word 'Singapore' mentioned several times, and one guy even sold his mobile phone in exchange for this foreign currency.</quote>

It turns out later that most of the people eagerly buying the worthless foreign currency are in cahoots with the seller, and a few unlucky stiffs end up handing over their RMB for Brasilian <span lang="pt">reales</span>.  Several times in China (lately just north of the Xinzhuang metro station, and also once in Mexico City) I've seen a dude playing the shell game--which cup is the pea under?--surrounded by obvious co-horts excitedly shoving money left and right in hopes of enticing a by-stander to throw in his own money.  Every time, I wonder how naive one would have to be to be blind to the clear teamwork at play in that situation.  But then, given my past history of being taken in on various occasions, I'm not one to talk.