When I was in college in Austin, we carefully avoided people talking loudly to themselves as they moved down the street. There was the large man who softly mumbled as he cut his eyes at your swiftly passing form. There was the man who knelt on the same corner every afternoon beseeching the heavens, wildly gesticulating, eyes glued to the sky. There was the woman who would snicker as you walked by, and another who told you what hell would be like.
Now, almost none of these behaviors mean you're probably crazy, off, of a different reality. Really, anything except the kneeling just means you're on the phone.