An Asian girl with big boobs and/or ass. Finding Asians with these assets is difficult, thus the "rare" part. Also based off the item in the Pokémon series that is hard to find.
John: "Yo did you see that Asian girl?!"
Tyrese: "Yea bruh she's a total rare candy. Biggest tits on an Asian I've ever saw."
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi