derivation of the word == 

 heard years ago that in the old days when a person was placed in the "stocks" for adultery a sign was placed above his head which stated-"for unlawful carnal knowledge"- the authorities were tired of writing all of that so they changed it to f-! 
 :That's a well-known fake etymology, and it's discussed in the article: Fuck#Fake_etymologies. Acronyms are a recent invention in English, so most stories about a word originating from an acronym are fake.   

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