Whilst I agree with Ethel, I can see where some of them are coming from. Some customers just have to be witnessed to be believed. They treat the checkout and shelf-filling staff like scum and speak to them as if they are the lowest of the low, and their supervisors don't treat them much better.
Saying that, there's a woman who works at the cafe at Tesco, Beaumont Leys who told me I couldn't have macaroni cheese with my jacket spud because 'they're two different meals'. I said in that case I would buy them as two separate meals. "You can't do that," she says. "You don't have macaroni cheese with jacket potatoes." Then she wondered why I walked off and left a tray on the counter with our two meals on it already served but not yet paid for. I wonder how she explained that one!