Yes, even the evil behemoth Starbucks can be subverted.

Every Starbucks has somewhere near the counter a table laden with wooden stirrers, napkins, cream... and thermoses of milk to be added, supposedly, to legitimately purchased coffee. Often, there are also shakers full of cinnamon, cocoa, and vanilla powder to flavor said legitimately purchased coffee. Some Starbucks (I point to the one in Long Beach as the most extreme example I've seen) also have at this table an urn full of hot water.

So, swipe a cup from the stack behind the counter -- distracted salepeople are entirely unlikely to care -- or bring your own, and have Starbucks treat you to a tall, cold glass of milk, or hot cocoa, or any weirder combination of flavors and liquids. And toast to urban scavenging.

Incidentally, this is increasingly possible at many faux-indie chain book or music store-cafés, such as Borders or Tower.