No, no, I insist you use this condensed milk instead of soy for this latte

The Really Big Guide To Secret Menu Items - Consumerist:

"Starbucks: Starbucks will make you absolutely anything you want no matter how insane it is, according to our tipster.
'Baristas might try and tell their customers that no, we can't do that with the blenders. This is a lie. Starbucks corporate policy is that the customer is ALWAYS right (even when the request is stupid). If you really insist that you want your iced soy latte blended, the baristas HAVE to do it. If they continue to refuse, ask to speak to a manager and either they'll realize they're about to get in trouble and will fill your request, or the manager will come out and politely tell the barista to make the customer happy.

Absolutely any concoction that you can think of (involving any type of milk, syrup, coffee, etc.) will be made for you. The limits to Starbucks 'secret menu' are merely the limits of your imagination. You can even bring supplements from home and ask the barista to please include that in your drink.' "

read more hidden menu items!
http://consumerist.com/consumer/secret-menu-items/the-really-big-guide-to-secret-menu-items-239708.php