Originally stems from the last name of a notorious slumlord/small business owner in the Fairmount section of Philadelphia. Said owner knowingly created shell corporations and willfully filed bankruptcy in order to swindle tenants and investors on a large and expansive scale. (1)The term has since evolved as a means to describe a situation in which one party knowingly misleads a second party with the intent of stealing. However, most recently (2)the term has also developed as its own expletive.
(1) Bob: "Did you hear about Harry?"
Mike: Yeah, the bank took his house after the ARM (adjustable rate mortgage) interest rate went up and he couldn't pay.
Bob: I know dude, they totally "Younised" the shit out of him.
(2) Jerry: God Damn F*&^ing piece of Younis!!!
Carl: Whoa man, whats the matter?
Jerry: Nothing bro, my car won't start..its the biggest piece of Younis I've ever owned.