Customer: “How many concurrent users can use this app?”
Me: “web tech is stateless. (Insert explanation) So concurrency is meaningless.”
Customer: “yeah but how many concurrent users?”
Me: “infinite as long as they aren’t interacting with the server.”
Customer: “but how many?”
Me: “400”

Introduction:
Privileged in this context means logged in and have a administrator-confirmed access.

Customer calls us: Why do I see prices in my shop? I should have been privileged first to see them. Looks to me that you did not make prices only get displayed when I am privileged.

Salesman: Sure we did this. May I asked whether you are logged in right now?

Customer: Of course. I am testing the process of placing an order with my test customer account.

*crickets*

Customer: I am so sorry for calling. You are right.

The site I work on is a market where you can buy magnets for dolors, insomniaque, bla bla bla (I don't believe a sec in this).
Just saying that to settle that 80% of our customers are +45 years old. They weren't born with a computer in their hands, and they sometimes manage to make a lot of mess in the site.
We are based in France, and we sell the most in France (no shit) and Switzerland. And this is the third time that a Swiss pass a command, puts all her address in Switzerland EXCEPT for the country (still on France) so she doesn't have to pay the shipping fee. I should do something about that, like a regex when verifying the zip code, but I have more urgent work to do, and the best has to come.
This smartass doesn't know she is the joke, because by saying she is in France, she has to pay the VAT that she wouldn't have if she said she was in Switzerland. She buys in general for around 350 €, so she has ~ 70€ (20%) in VAT, and she would only pay 14€ in shipping fee.
Maybe one day she'll see how dumb she is (my boss already mailed her so she pays attention to it, no change). But I think I would have set the regex by then.