This phrase was derived from my English class. We were reading Twain, and David was confused by use of the word 'hither'. He goes, "what, is that like ghetto-speak or something?"
Then this brilliant classmate of ours (me) goes, "fo hither my nizzo". Therefore:
fo hither my nizzo - phrase - used to provoke the anger of a loser who uses old-school speech, as in the word 'hither'.
Jim: Come hither, sweet patriots!
John: (mocking) Fo hither, my nizzo! LOL bastard!