Queuing is nothing special in Japan. Every day, television programs show long lines of people queuing for up to one hour even in front of regular noodle shops, only to finish their food within less than ten minutes. Why Japanese people queue so often? Do they love it? Probably they do. According to Japanese people, just like an excessively high price can evoke an image of equally high quality, long waiting lines act as an indicator for popularity, reduce availability and increase the subjective value of a good. Thus, for many Japanese customers, waiting lines are probably the most effective advertisement. For example, in an article published in The Japan Times in summer 2007, a Japanese woman confessed that she enjoyed queuing outside shops and restaurants and that she usually joined the line before asking the person in front of her what kind of product was sold. Standing in line also increases and extends anticipation until—yatto! (finally!) —patience is rewarded with the desired product. But when taken to an extreme level, the product one is actually queuing for ceases to be of any importance at all. There are also some customers who are unable to queue or who are unwilling to wait, thinking it' s a waste of time queuing in a line. What could they do? They can rent a queuer who will stand in line and purchase the desired product for them. Obviously, this service is not free of charge. Some service companies who offer all kinds of unusual service provide rentable ' queuers'. What' s more, in addition to providing queuers to individuals, the service companies also provide queuers to some shops to increase the image of a hard-to-get product and make customers want to join the line by forming or extending lines. Therefore, waiting lines have become a marketing tool and it would not be surprising to find professional queuers in a line. Some people view it a pure speculation, but they can't deny that it really works and the wage of a few professional queuers to keep the line in shape would be a minor investment compared with what would happen if the queue suddenly disappeared. However, success is not always guaranteed because the attractiveness of waiting in line can easily backfire if the desired product does not meet expectations. What is the marketing tool appears in the text?