def O.J., n. — Green’s Dictionary of Slang

def O.J. n.

[‘In “Rapper’s Delight” the term “Death OJ” is used. In current slang “death” means something good, while “OJ” is a ref. to a big car. Erstwhile football star and all-around adman O.J. Simpson does Hertz commercials featuring Ford and Lincoln Mercury cars. If we add “death” to Ford and Lincoln Mercury cars [...] we come up with the “Rapper’s Delight” character driving off in a Lincoln Continental’ (Nelson George, Buppies, B-Boys, Baps and Bohos, 1992)]

an extremely smart, fashionable automobile.

1979		Sugar Hill Gang ‘Rapper’s Delight’ 🎵 Ya say im gonna get a fly girl / gonna get some spankin / drive off in a def OJ.
1985		Slick Rick ‘La Di Da Di’ 🎵 We can go cruising in my OJ.