From nekholm, Tales From Retail:
A few years ago, a stubborn customer (SC) approached me, and the conversation went something like this:
SC: Hello, where are your windshield wiper fluids?
Me: Right this way. I show him where they are
SC: Yes, I saw these, but they were supposed to be on sale. A few cans for X€. (Customer couldn't remember the exact amount or the price)
Me: No, I don't think they are.. Checks the computer. No, it must have been one of our competitors.
SC: No, it was your ad.
Me: Shows customer the ad from that week. No, these are the items that are currently on sale, there's no windshield washer fluid in here.
SC: No, it was another ad, I got it in the mail today.
I was a little unsure before, but now I'm getting very confident it was someone else's ad. This happened on a Wednesday, and our ads are delivered on Mondays. Also, it was supposed to be Y cans for X€, and back then, we didn't have those kinds of sales on the fluids.
Me: It must have been a competitor's ad, our ads are delivered on Mondays.
SC: It was your ad, and I got it today.
Me: Well the computer doesn't show any signs of the fluids being on sale, and I haven't seen any ad with it, so it must have been someone else's.
SC: Fine, if you won't give the discount to me now, I'll drive home and get the ad. And when I return, you're going to refund me for lost time and gas. (He lived in another town, 20-25 miles from our store.)
Me: OK, but I'm pretty sure it wasn't our ad.
The customer finally leaves, and I get back to whatever I was doing. When I got home, I checked the mail, and what do you know. There's an ad from Competitor1, and they have a sale on windshield wiper fluid! Five 5 liter cans for 19,90€. Our price is (or was, back then) 3,99/can, so five cans would have cost 19,95. The customer didn't return that day, and I don't think he ever did.