A Chinese term used often in online novels.
It refers to someone who is secretly evil, sly or manipulative. Secretively is the key point: most people won't realize the person's true nature or the person will portray a different image.
The term exists because someone will only know what that person's true nature is only after "being eaten up."
He was so black-bellied that after finally getting her to take the initiative to show good will, he pretended not to notice.
1. adj. meaning "cowardly, wuss-like"
2. A slightly archaic emphasizer for an insult, right up there with "godforsaken" and variations of the word "freakin' "
Used to call someone a coward in ADDITION to another insult.