I work as a cashier at a members-only warehouse type store. This story took place last September, but I still remember it like it was yesterday.
It's a normal Sunday afternoon, kind of busy but not unmanageable. I have about 25 minutes left in my six hour shift when She approaches. From here on, I'll refer to her as Coupon B*tch (CB).
Throughout the entire transaction, she seems nice enough. Her order ends up being about $300, almost entirely food, about half of it cold.
Then she hands me her pile of coupons. As I start to scan them, I notice that about half of them are for items she didn't buy (wrong brand or even items that just weren't there), and that there are multiple duplicates of each one (we have a strict policy of one coupon per item). To save time, I go through the pile, scanning whatever I can and setting the rest aside into a pile that I'll give back.
I turn to her, and start to explain why I rejected certain coupons.
Me: Unfortunately, you purchased a different brand of this item (I don't remember exactly what it was)
She's fine with this, although I think she hoped that I wouldn't notice and just give her the discount on the other brand.
Me: This coupon could only be used on the pre-packaged 3 pound block of cheese, not on the deli product (which she had only bought about half a pound of).
CB: Well that's ridiculous, get me your manager.
I flash my register light to call over a manager, and as I'm turned around, I hear CB whisper to her friend:
CB: Never had a f*ing problem before, but this f*ing nerd won't take my coupons.
I chose to ignore her for the time being, knowing that the manager who was coming over wouldn't give in to her. In the meantime, I go through a few other coupons, explaining why I couldn't take them and showing that she had not purchased the item.
When the manager arrives, he asks me what's wrong. CB decides to answer instead:
CB: Oh hi honey, this kid won't take my coupons.
Keep in mind that I'm a student, but this manager can't be more than 10 years older than me. He asks me to see the stack of coupons, and I briefly show what she had purchased. At one point, he asks me to get a bag of deli meat from her carriage so he can check it against the coupon, and it falls onto the floor.
CB: DON'T MANHANDLE MY SH*T!
Mgr: Ma'am, he's just doing his job. We can't accept these.
CB: Then, you know what, f*ck this store, f*ck you. I'm leaving. Have fun putting all my sh*t back.
And she stormed out, leaving us to put back a carriage mostly full of refrigerated items. I was pretty shaken up, to be honest. I had been at the job for a few months but this was the first time I had been personally insulted. I'm pretty short and thin, and I wear glasses, so I assumed that her "nerd" comment was directly attacking my appearance. Thankfully, the next customer in line had seen everything and he could not have been nicer. I left 20 minutes later fuming, and a year later, she's still probably the worst customer I've ever had. I guess it makes for a good story to tell now.
BONUS: According to a coworker who works at the customer service desk, located about halfway between the registers and the store exit, CB was still ranting about us on her way out. I haven't seen her since.