A diabolical, evil and cunning person, that you hate because he ruins peoples lives and has no morals. They are the world biggest crooks and are real hypocrites.
When the DEA raids dispensaries of weed (typically in California, where weed is semi-legal), the agents - who are dressed head to toe in black - stand in a line and hand things down the line very fireman-water-bucket-line style. It looks a lot like a black snake slithering.