Spenny, mental health issues?
In the first season Spenny seemed like a calm, fairly normal kind of guy with a few paranoid and neurotic sides. But all in all, pretty normal.
He gradually as the show progressed became more and more eccentric, paranoid, neurotic and dumb to the point that make me believe that he at least have some mental health issues.
Either he had a nervous breakdown from how much he is *beep* on the show or he's acting.