Linux, duh

We don't talk about GNU here

idek

Anything I like, it can't hear me.

There is by far not "the" operating system with that kernel. Collectively, I refer to distributions which provide a Linux user environment in a major way (so: Mint/Arch/Gentoo = yes, Android = no) as being Linux.

NixOS, in my case, but you could also call it Debian, Arch, or anything else. If you mean in general, I call it whatever name pisses off Richard Stallman the most.

whatever it calls itself

Either Linux or GNU/Linux (funny you mention this, as I post the GNU/Linux copypasta all the time). Not all Linux distros are GNU/Linux, though. 😉 (Void Linux being one example.)