A mental dwarf. A total village person with an exaggerated and unrealistic view of himself or herself.
My uncle got his MBA more than twenty years ago, and he makes good money, but despite being in his late forties, he still thinks, talks, and acts the same as when he was in grade school. He is always making ethnic slurs against his minority neighbors, and I heard at work he likes yelling at the new hires.
That’s because he is a connecticut. I try to stay away from those kinds of people.