A shyster is someone who might rip you off or do something unethical in order to get his way.
A used car salesman might tell you a car is a thousand dollars, but when you read the fine print, it turns out you’ll pay a lot more. That salesman is a shyster — someone who lies and deceives for his own benefit. The word comes from the German Scheisser, which is a vulgar term for “worthless person.” Although it contains the word shy, it actually sounds more like heist, which makes sense, since shysters are basically trying to rob you.
