Yeah, they want to just give you the cup and keep the can, but if you tell them to fork over the can, they will give it to you.
Up North if you order tea they’ll bring a 6 oz cup and a tea-bag. Here in North Texas when you order tea they ask sweet or unsweet then they’ll bring a 16 oz tumbler with ice and keep topping it up until you ask them to stop (it’s a tip getter).