To be fair, the cashier did give you exactly what you asked for. I work in a place kind of like in N out and you have no idea how many stupid people come in and ask for a "plain hamburger" but what they really mean is a regular hamburger, as in exactly how it's written on the menu. So, sometimes I have to ask people to reiterate, which makes me feel stupid but if I don't, they order the wrong thing and get pissed. Oh but my personal favorite is when people ask for a double burger with cheese, and WE HAVE A DOUBLE CHEESEBURGER SHOWN RIGHT UNDER IT ON THE MENU. ? Anyway, just try to see things from other people's perspectives. It's not as easy as it looks.

Because of many low carb dieters, it's not uncommon to have people request burgers sans the buns. If you don't want pickles, and condiments, then just say that. You got what you asked for.

I'm not surprised. A lot of people are skipping the bun lately, cause of ' junk low carb' (it doesn't fall under paleo cause paleo is anti-junk food).

In OP's defense, they did originally say "plain cheeseburger" which is a bun, meat, & cheese. It was not "plain cheeseburger, no bun." It doesn't generally occur to people who aren't fast food workers that clarifying "just the meat & cheese" could be understood as without the bun since it's not really a burger without one. Ideally the cashier should have asked for clarification again, but especially if it was busy it's understandable they didn't.

You deserve it for being fussy. Just eat the burger as it comes from the menu.

One time my mom ordered a cheeseburger without the meat, she had to explain that she was a vegetarian, the two Mexican employees who barely spoke English gave her two buns with lettuce

The same thing happened to me! At Arby's, I told them I wanted the roast beef with Swiss cheese only. They plopped those two things down on the wrapping paper and that's it. It's very unsettling to know that this has happened to so many other people. Common sense is becoming a thing of the past.