Here is the answer on the Polish instance directly from @ernest, kbin's creator. For reference, he was being accused of being a gun lover based on the name of the Polish instance "karab.in" and "magazines," as well as his Monty Python profile pic with a gun in it.
Here are the relevant sections from Ernest on the origins of both kbin and magazine:
Hey, I'm the admin of kbin.social. The name "kbin" comes from the Linux "/sbin" directory - I've mentioned it multiple times before. The name of the Polish instance - karab.in - does indeed reference a rifle, but it's just a play on words, and it was actually chosen through a survey among other domains. It's simply easy to remember and sounds nice in Polish. There's no place for nazi bullshit on my instances.
On the other hand, the name "magazyn" refers to the virtual edition of a late 90s gaming newspaper :D
So /sbin from Linux + k from karabin from the Polish word for rifle
But the creator doesn't want it the instance to be seen as rifle-focused or otherwise militant and violent, so it just carries the "rifle-wielding polish linux user"-name without wanting to focus on militant Polish nerds.
according to ernest it stems from /sbin. though one of the early instances was named karabin based on the karabine gun and thus shortened to kbin (or rather expanded from kbin).
Ernest has actually said that the name "magazine" isn't gun related and that it's a reference "to the virtual edition of a late 90s gaming newspaper" (see this thread and my other comment for the full story)
Someone in that thread also explains that in Polish the names are different:
Polish word "magazyn" means storage or newspaper, but "magazynek " is a gun mag.
Fun fact, Kbin is actually where all the big Ks from all the signs went when all the Kmarts shut down. Only, it turns out they were made of meat all along, so the refrigeration costs have been pretty significant... Kbin only runs the social media platform to earn enough money to pay for it all.
I'd read somewhere that there's some sort of Linux programming reference in the name, but I don't know anything about Linux so I can't quite remember. Don't quote me on that, though
Linux has directories (folders) that contain programs. The two major conventions are /bin (short for binary which is another name for an executable program) and sbin (system/super user binaries).
Kbin seems like a play off of that, don’t know what the k implies tho.