Some words have dubious or unknown origins, and here we discuss them.
The word bonfire (or bone fire) originates from sacrificial pits used ancient Babylon and by the Druids.
Bonfire does indeed originate from "banefire", which meant "bone fire", but this referred to a pile of burning bodies that were being burned during the bubonic plague. This had nothing at all to do with sacrifices. The bodies were often burned in pits and then covered up. Let's also not forget that neither the Babylonians or Druids spoke English, or any form thereof.
Cunt originates from the Latin word Cunnus, meaning "vagina".
The Latin use for "cunnus" could originate from the Latin "cune" meaning wedge. In any case the word "cunt" likely originates from Proto-Germanic, that is the father of all Germanic languages, as most other Germanic languages have cognates for the word: Kunta (Swedish), Kunte (ML German), and so forth.
The term 86 originates from the New York liquor code, Article 86, which provides a list of reasons you may remove someone from your bar.
While this is incorrect, it isn't that far off. It originates from the 1930s in restaurants, likely the result of rhyming slang for nix (none), when an individual asked if something was available.
The word fuck originates from the phrase "Forbidden Under the Consent of the King" or some other phrase.
Like the word cunt, this word likely originates from Proto-Germanic as there are cognates with other Germanic languages: ficken (German), fokken (Dutch, to breed), fukka (to have sex).
The word shit originates from the phrase "Stack High in Transit" or some other phrase.
Like with fuck and cunt above, this word originates from Proto-Germanic, and has related terms in other Germanic languages: skit (Norwegian), Scheiss (German).