Can someone please explain me all these frontend/backend jokes? Oh my God I see like 10 of them every day and I can't understand what the hell they mean. I'm a full stack developer, I write frontend and I write backend. In my life I saw good code in both sides and bad code in both sides.

Why the hell the frontend should look nicer? What's the reason behind? Are maybe developer afraid that someone could inspect the code and write a cleaner one? Do they mean "graphic UI" by frontend and so they aren't talking about code? Are frontend languages better? WHAT THE HELL IS THE REASON