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 Ricecracker!
Me: He's going to be rich soon, he's upgrading to Opium!
A person of Caucasian descent (White) who is obsessed with all things Asian. This includes the obsession with Asian culture, Martial Arts, people,language... etc. Will usually be seen with an Asian girlfriend, boyfriend, wife or husband. This word has a similar meaning to "Rice Queen" but can be applied to both genders.
If you're the only white guy or girl at an Asian wedding, you're probably a "Rice Cracker" :)