I've worked at McDonald's for a couple of years, so I've had my fair share of stupid and annoying customers. I'll share a story that happened just last week.
Some lady came through the drive-thru earlier in the day, but then she called in later complaining that she was missing some McNuggets. The floor manager took the call and acted really nice and understanding about it all. After she hung up, she told the rest of us what was going on AND mentioned that the lady over the phone had been screaming and cursing at her the whole time. Yep.
So the lady comes in about fifteen minutes later to get her food replaced or whatever. (I was busy with something else at this point, so I don't know if she got just the nuggets or her whole order replaced. Doesn't matter, I guess.) Anyway, my manager dealt with her and was nice about the whole thing. I don't believe the customer was being nasty this time, despite the way she acted earlier.
The lady leaves after a bit and my manager disappears for a while to do whatever. When she comes back up front, she tells us she got another call from the customer. Apparently, all the lady said was "You're a fucking *****" before hanging up. I don't understand this at all. My manager was being understanding, kind, and helpful, so why call her and to tell her that? Ugh.
Man, I envy the people who can do that whole "kill them with kindness" thing so easily. If a customer pisses me off, I just leave and let somebody else handle them because I can't keep my anger in check so easily.
Oh, and I've also had a customer pretty much insist I was lying to her about tea, too. She wanted half-sweet, half-unsweet. I make it, she drinks it and insists that it was all sweet. I hate people.