[theo_luddite]

Why are they called Yam Yams,Theo?

Ha ha, it's what the Brummies, the Baggies and what anyone else from the Black Country call Wolverhamton folk. Yam comes from you am, which really should be you are, and you'll often hear folk round here referring to someone they are talking to as 'yam a ..... something or other .. yam' or maybe something like 'yam saft yam' - hence Yam Yams. On the other side of the great M6/M5 divide they are more likely to say you'm rather than yam.

Just a quirk of Muddled England dialect.