An Asian guy (usually Chinese), who smokes
crack because he can't afford opium.
The term was most likely coined during the Opium Wars, during which the corrupt Chinese Government imported opium to feed it's own people. Those in power, made huge profits. Those who couldn't afford, turned to
crack. Hence
rice cracker was born.
My
Friend: Gee, your Uncle Chong is such a
Rice cracker!
Me: He's going to be rich
soon, he's upgrading to Opium!