A friend of mine that is a really great player was doing this a couple of months ago in a big nineball tournament. But he was doing it because he was hammered and/or very stoned. I've never seen him like that on a pool table, and I felt very sorry for him that day. I asked if there was something bothering him, and he said it wasn't worth talking about. It was weird, but on his final stroke he'd lower his head like he was nodding off, chin down and then a final head turn to the right. It's not a part of his game, and probably not what you are talking about because it sure wasn't doing him any good.