"OFF THE HOOK", a Dictionary of African American Slang. In Japanese. Being sold in the remainders section of a WHSmith a sleepy provicial Norfolk town.
The weirdness quotient was just too high, and the price (only £2!) was too low not to buy it. Plus it's author, Randall C. Miller Junior, looked cool!
I wasn't disappointed. In fact I think, per penny, it's one of the funniest books I've ever bought.