A person who fancies himself a savior or god, like Jesus. However, unlike Jesus, he is only concerned with his own welfare. Ironically though, by taking whatever he wants and worshipping himself, he breaks almost all of the Commandments.
Al: How about Joe, taking my things without asking! And he's the worst player on our team!
Mark: Don't tell him that though. He thinks he's great... He's such a Mesus.