I think it's cute when customers think we give a fuck when they say "I'll never shop here again."
Case in point->
Me: Is this going on a Sears card today?
Me: Alright, so you get an extra 30% off of any clearance items you have today.
Woman: No, the sign said 40%.
Me: The sign said 40% when it's on a Sears card and 30% with anything else. I can set you up with a Sears card if you want.
Woman: Seriously? I have to have a Sears card in order to get the 40% off?
Me: Yup. Again, I can set you up with one. It only takes a minute.
Woman: That really pisses me off. I'm never shopping here again.
Me: Alright, so your total is -whatever-.
Woman: Did you hear me? I said I'm never shopping here again.
Me: That's alright. Your total is -whatever-.
Woman: So you don't even care that you're losing a customer?
Me: Not at all. How are you paying?
Woman: Really!? I said that I was never shopping here again, and you don't even try to keep my patronage!?
She paid and stormed away and my manager, who saw the whole thing, laughed and said "What the fuck did she think you were going to do? Grovel at her feet? Fuck right off."