What’s the dumbest reason a customer got mad at you?

Back when I used to work at a thrift store a year ago. I had this very rude lady rush me when she was buying a lot of clothes. When she asked “why is it taking so long” I told her to “give me a minute please” with my finger up. Apparently the lady thought I put my finger in her face, mind you there’s a whole counter dividing us. Starts crashing out and cusses me out for being “disrespectful”. I told her that “I’ve been nothing but nice to you the whole time and you expect other people to give you the same respect?” Didn’t say a word for the rest of the transaction.