De Perguntas frequentes do Ocean's 13 do IMDB :
It's not well-explained in the movie. However, it implies a sort of 'gentlemen's agreement,' an unbreakable code between the members of an exclusive group of businessmen who have been operating in Las Vegas since the days when (Frank Sinatra) was a Vegas performer and a man's word was his bond. The inference is that one does not attempt to fleece another member of the group. Clearly, Bank screwed over Reuben by making him sign over his investment for a small cash payment. Incidentally, Frank Sinatra played the role of Danny Ocean in the original Ocean's Eleven movie.