Someone who is stupid, and who doesn't think before they act/speak. Spoonerism of "mentally retarded," and has come to mean someone who isn't retarded, but acts like it.
One coming from a school of Millard Middle School, with bad food, dirty EVERYTHING, trailers for classrooms, crappy teachers, and basically no education. But they are really funny and have good personalities.
A gansta term deriving from Australia, a compliment used to describe how thuggin someone is. Originally millard, the phrase has been changed by todays kids.