Sam can't help but feel a little hopeful with that impatience. It means that the old Castiel, the one that would have snapped at him, isn't entirely gone. Little flashes like this are good.

"Tell you what," Sam says after a moment. "I'll let you borrow some shorts and a shirt and we can go get some coffee, at least. Maybe an apple. After that, I can help you figure out if you're hungry or not and we'll go from there."

It's an easy decision to start with, letting Sam do most of it. "Later, we'll go to Wal-Mart and get you some more clothes, too." Because Castiel's going to need more than what they have, at least for the time being while he heals.