A "triple sixer" as in 666 or "related to the devil", is a generic blanket term for a "bad person", possibly coined by Aesop Rock. Stemming from the stereotypical christian ideology; devils and demons being evil and god and angels being 'good'. Anyone who might try to hold you or your ambitions back from something positive happening or some progress being made is also "triple sixer". Just anyone negative to you.
All these fuckin' triple sixers make it hard to even walk around on the streets anymore man!