Fame
Mrs. Shlobovitz will know you. She's 83 and seeks you out for the eighteen seconds of interaction she has (with anyone) each week. You're famous to her. Unless you're gone, in which case she goes to Bob in aisle two. Or if he's gone, she goes to Moishe in aisle seven.
The important thing is that you are famous…to her. Or…well, she knows who you are, more or less, for eighteen seconds. Beep.