Retail workers of the UK, pls spill the beans

Working with the public is never fun, and I worked in retail for years. I just wanted to ask; anyone who has worked with the public in popular UK stores, what are your funniest (or worst) stories of interaction with the general public, that made you lose faith in humanity.

For example, I worked in a party store in a small Essex town for 3 years, and often (on a monthly basis) I had ppl coming in to complain our balloons didn’t float, when they were trying to blow them up with air. Top that.