To say someone is a "roman moroni" is to say that he or she tends to use slang words or phrases without really knowing the meaning, or even caring to know the meaning.
Commentary: We all know "roman moroni's" and we may be quick to point out their, well, moronic behavior. Truth is, urban slang is created by "roman moroni" type people who are either so cutting edge or so brainless that they have the ability to make standard vocabulary conform to themselves and not the other way around. And the true genious "roman moroni" types are setting trends that impact modern vocabulary for all eternity.
"You lousy corksuckers. You have violated my farging rights. Dis somanumbatching country was founded so that the liberties of common patriotic citizens like me could not be taken away by a bunch of fargin iceholes...like yourselves."
"You fargin sneaky bastage!"
Famous "roman maroni's":
George W. Bush - "They misunderestimated me."
Jeff Spicoli - "We left this England place 'cause it was bogus."