No one should have to kiss my ass just because I'm buying groceries from them. It makes me uncomfortable when service personnel older than I am call me "Sir". I particularly don't require the overly familiar attitude adopted by Safeway clerks, just because I entered my Club Card number and they read my last name on the display.
So here's what I've begun doing:
Clerk: Thank you, Mr. Keane.
Me: Please. Mr. Keane is my father's name. Call me Sean.
If that line gets you laid by an unsuspecting Safeway cashier you should send Wes Anderson a fruits basket.
I have the same issue here with old lady clerks using usted to address me. Though I do insist on being called Don Jason del Norte.
The Safeway clerks have this habit of referring to me as "Mister Love" whenever I pay cash.
When I don't pay cash, they refer to me as "that asshole who can't ever get his PIN right".