The word
Yen also has another meaning in the
English language: It means
a craving.
This use of the word dates back to the days when Opium use was legal in Britain. Opium addicts used the slang term yen-yen, derived from the Cantonese "yin", (Opium), and "yan", (craving).
The word is used in the context of "having a yen for something".