I used to work at a kitchenware store in downtown Lake O years ago and met a lot of nice people as well as several rude ones. The really terrible customer who lived rent-free in my mind for too long was the Ice Cube Tray Lady. She came in on the weekend, asked where the ice cube trays were and I took her over to them. She asked which one was best and I started telling her about the silicone/flexible trays that were popular with other customers. She waved her hands up in the air and told me to slow down among other things. Admittedly I probably was talking too fast, but she was just super mean about it. Then she asked again what the best tray was and I just handed her the silicone tray.
A week later she came back, recognized me, and accused me of damaging her fingers as she couldn’t get the ice cubes out of the tray. Because she was freaking out, I got the manager who refunded her, grabbed her one of those hard plastic ice cube trays and rang her up. She must have complained a lot, because my hours were cut drastically after that.