Cracker bait is the opposite of nigger bait. Cracker bait is an African American female that, for any number of reasons, attracts white males. This may be a natural trait that she has no control over, or a deliberate trait due to an attraction to white males on her part. Signs of cracker bait are a black girl dressing in traditionally "white" fashion, listing to "white" music, hanging out with white people, and speaking without any trace of Ebonics.
"What's up with that one black chick in calc who always sits with the white people and talks in that really cutesy voice?"
"Dude, she's cracker bait. She loves the white chocolate."