My inner bullcrap siren goes a blazing. Does she think she's doing me some favor making a sandwich for me? I'll fucking buy whatever I want wherever I want.
Unfortunately this inner dialogue doesn't last long enough to prevent me from saying "I don't have to buy anything here at all, ya know."
Her eyes turn into dinner plates. "oh no no no! We like to have you. We hope you come back!" and goes on and on, making me feel more prickish with every demurring apology. So I try to make good by complimenting her on how fast they made the sandwich and how they have the chips I like. But I still feel like a big dick.