Tattoos in a very visible area of the body. Originally used to describe knuckle tattoos, the term has broadened to inclued ink work on hands, neck, face, forearms, etc.
The term makes the obvious allusion to the fact that, in many segments of American Society, persons with the tattoos in question have somewhat limited career opportunities.
"As soon as she spotted my Job Killers, the interview was pretty much OVER"
"But I'm the most qualified candidate! Must be the Job Killers. Don't descriminate based on the colors of my skin!"