It happened not even a week ago.
There rarely are persons speaking English at the register (cashiers as well as customers), since I live in the very east of Germany in the countryside, so here's barely any tourism.
What's more, my store is located ten minutes from the border to the Czech Republic and Poland, it's a crossing of three countries there.
Now to the story: I had a Czech/Polish woman at my register, surprisingly speaking English with me. She was a very sweet, young woman and we small talked a bit. She bought two carts full of items, which is normal, since Polish/Czech like to shop in Germany, due to the items having a higher quality (according to them).
Now, the thing is, there were a lot of customers, since it was one of our busiest times of the day. The woman was very ashamed for her buying so much amd holding up the line, and she was very nervous.
I always tried to keep her calm. She's a good customer for buying so much; she doesn't need to be ashamed; it's alright; she can take her time, since the others can also get in line at another register.
It seemed to help and in the end I helped her with her baging, which we normally don't do in our store. She was very kind so I wanted to give her a good service and make her day a bit better.
After a while, we were done.
Woman: I'm so sorry for holding up the line, I didn't mean to stress you...
Me: It's alright, really :) It's my job after all.
Woman: You did a very good job. You're very outstanding and so smiley and friendly!
I was flattered and it really brought a big smile to my face, which lasted until I clocked out.
After I clocked out two hours later, it turned out that she left a message at the customer service desk for my manager, praising me into heaven, what an outstanding worker I am and how my managers better should aknowledge that.
And what's more, she left some sweets from her shopping for me to take home!
This is probably the sweetest customer I ever had until now and I really appreciate it. Makes me smile until today and I hope every retail worker has a customer like this at least once!