Someone generally, but not always, of Jewish decent. Often has no shame in stealing from friends for minor financial gains. Willing to lie, connive and back stab for their own personal gain. Stingy in nature.
person 1: Dude, why did you just steal 50 cents out my change jar?
friend of person 1: What are you talking about? Why would I do that?
person 1: I just saw you do it with my own eyes. Empty your pockets!
<friend of person 1 empties his pockets, 50 cents falls out>
person 1: My god you are such a j-rat