My worst customer ever happened at my first job. It was a truck stop in Virginia and I was working as a cashier at the Arbys. Let's not go into how horrible the management was, or bad the truckers usually were. I got hit on every time I worked by nasty old trucker dudes.
So this customer was a trucker, and lucky me, I was the only person on the register that day. He came storming up the counter and demanded, not asked, for a bowl of chili. That was not an item on our menu, and I politely told him so. He got very angry with me and started yelling and cursing me out. It was hard to keep my cool, but I managed it, somehow.
Next he asked for a baked potato. Those we carried, but as it was nearly midnight we hadn't put anymore out to cook. I calmly explained this, and he went into a rage and tried to come across the counter at me. My manager finally took over then, and he was banned from coming back to Pilot.
I spent an hour crying in the back, and they had to have somebody walk out to my car with me afterward because we thought he was still hanging around.
I still remember you, trucker dude. If I ever see you again, I'd love to give you a bowl of hot chili. In your face.
Of course, he's not the worst.
I will never get why anybody thinks that just because one works in customer service, that person is automatically lower on the food chain.