A yammo can have a few differentdefinitions, depending on context. In general, it is used to refer to a person who is or is acting like an idiot, fool, moron, dimwit, simpleton, tool, lunk head, asshole, jerk, etc.
When I think of James, the first thing that pops into my head is beautiful. He really doesn't notice how beautiful he is and how much people think he actually is. There is no reason to hate on this boy because he doesn't deserve it. He is human and every human is beautiful INCLUDING JAMES.