When he tries to be funny, it's always really lame, either a tired joke or something incredibly cliché. And he always says things as if he's invented something groundbreaking.
He constantly states the obvious – he says things that everyone already knows, and he does it with the same attitude and intonation, as if he's just discovered America.
He also has coordination problems; he's kind of twitchy. And he often gets nervous for no reason.
And, of course, in his free time, he plays some online game. I don't understand how he manages; he should be treated the same way there as he is at school.
In general, these kinds of people aren't very smart naturally, but they compensate for it by memorizing things and being a stereotypical nerd.
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Why do you even care about him? I've never paid attention to people like that; let him live in his own world, it doesn't affect me either way.