I was working a backdrive at a fast food joint years ago, and older Karen comes driving in to give her order. Now, this location doesn't have a speaker due to a neighborhood ordnance, so all the orders in drive thru are taken face to face. She orders a double cheeseburger without onions, and I ring it in, complete her order, and send her on her way. About five minutes after she's picked up her food she comes back through drive-thru and says "they put onions on my burger". I apologize, print her up a duplicate recipt to confirm to her and myself that I rang it in without onions. I then tell her that if she goes up to the front window and tells the manager who's working up front that they'll replace the burger for free made correctly, but that I can't do anything about it back here. She does so and they give her a brand new burger and an apology. I thought that was the end of the situation, but boy was I wrong. Karen called the state government on me, by name, demanding I be fired. If I recall correctly I was told that she called the food safety department, the Chamber of Commerce and the governor's office. The franchise owner called to say that it turned out that Karen is allergic to onions, and she straight up accused me of deliberately ringing her sandwich in wrong and trying to poison her, then printing up a false duplicate receipt of her order to make her look like a liar (keep in mind that I read the receipt back to her and she confirmed it was her order). I didn't get along with the manager who was working at the time, but even he was like "that's complete [crap],, it wasn't even his mistake it was the kitchens and we fixed it for her". The franchise owner was told by whichever branch of the state government called them that Karen had demanded that I be fired. I wasn't, I wasn't even written up, but I did stop wearing my name tag at work when I could get away with it. TL;DR - got the state government called on me by Karen because the kitchen messed up an order, which got replaced free of charge. Could've been fired for a mistake that wasn't even mine.

When I was working retail, this one women had a big bag of coupons. Most of them were unusable because either they were expired or they were duplicates. She berated me because the system was rejecting most of the coupons. She called me stupid amongst other names, telling me I just wasn't doing it right. Then as a typical Karen would, she asked to speak with my manager. My manager came and asked what the problem was. The women ranted about how incompetent I was because I didn't know how to scan a coupon. My manager looked at the coupons and the coupons were the problem, not me. My manager [called] out the customer for being disrespectful for me and told the customer to leave the store. I hated working there but I'm so grateful that I had managers that totally didn't go by the "customer is always right" rule and weren't afraid to stand up for their employees. That was just one of many incidents.