This article last week by Tim Harford discusses price discrimination by Starbucks. Apparently, there is a size of cappucino that they do not list on the menu and you have to ask for specially: the "short" cappucino, which is higher quality and cheaper.
Making you ask for it is the way that they differentiate their customers: people who are more price-conscious are more willing to go through specially asking for the size.
This strategy is similar to the strategy of offering coupons. Another example mentioned in the article is a British grocery store, Tesco, that puts its cheaper store-brand of products in notoriously ugly packaging (again, more price-conscious customers will care more about the price than the packaging).
Any other examples of businesses trying to segment their customers this way? Any other explanations for why Starbucks would have that secret menu item?