His home is a mess. Papers lie everywhere. Dishes are left unwashed for weeks. He doesn't live with his parents and he's rarely home long enough to pay attention to such things so things just pile up. Eventually, he just gets tired staring at all of it that it becomes a pain to deal with and the mess just grows. Sometimes he describes the pile of (hopefully just) clothes in the corner of his house as the monster that will one day eat him (or something like that).