""A man sits alone on a bus. Another man gets on and sits in the seat in front of him. The man in front opens the window. The chap behind him is annoyed that he is sitting in a draft and that this person has opened the window with no thought for him, so he closes it. The other man promptly opens it again and the man behind closes it. This is repeated a few times more. When the window has been opened yet again, the man behind asks the other chap "Here mate, what"s your game?" The other man replies "Drafts and it"s your move". ""