[njbchbum]

you can see the rachel jeantel definition in this transcript from her piers morgan interview:
'MORGAN: Let's talk about creepy ass cracker. People have said that that is a phrase used by black people, cracker, to describe a white person. Is that true?
JEANTEL: No. Like I said --
MORGAN: How do you spell it, first of all?
JEANTEL: Cracker. Well --
MORGAN: There's no E-R, right? It's --
JEANTEL: No. It's A at the end.
MORGAN: C-R-A-C-K-A?
JEANTEL: Yes, and that's a person who act like they are police, who like (INAUDIBLE), who acting like, that's what I said to them. Trayvon said creepy ass cracka.
MORGAN: It means he thought it was a policeman or a security guy.
JEANTEL: Yes. Who's acting like a policeman and then he keeps telling me that the man still watch him. So if it was a security guard or a policeman, they would come up to Trayvon and say, do you have -- do you need -- do you have a problem, do you need help? You know, like normal people.

full transcript here: CNN.com - Transcripts

but where i worked in a great big city, the term referenced anyone with a flat azz - as in cracker!