FYI, the equivalent slang word to "pussy" in some other languages (including Spanish) literally means "rabbit."
What I've always heard In Mexican Spanish is
panocha, which literally means "ear of corn." Can anybody figure that one out?
I've always been impressed by the richness of profanity in other languages, compared to English with our "seven dirty words"--which keep being rehabilitated and require constant replacement. You can now call someone a "dick" or a "pussy" in prime time TV, and although "asshole" and "bullshit" aren't quite there yet, you hear
women tossing those words around in business meetings.
The Spanish insult roughly equivalent to the moderate offensiveness of "asshole" is
pendejo, but it literally means "pubic hair"!
How long has the slang been in common usage?
If you mean "pussy," it appears to have been around for more than a thousand years. If you mean the whole phenomenon of slang, it goes back into the mists of time, surely long before the technology of writing was invented. The Romans had it.
And how do slang words form? They arent like normal new words adopted from other languages, sometimes they are combined or changed from the same language or sometimes they are invented. How do they spread?
Not all "normal" new words are adopted from other languages. English, like all the Germanic languages, has a powerful word-building mechanism. You can cram almost any two words together, and if people understand you, you've been successful: doghouse, freeway.
Scientists, engineers and other professionals coin
acronyms like laser for "light amplification by stimulated emission of radiation." (Today people often use "acronym" and "abbreviation" interchangeably, but an acronym is pronounced as a word whereas an abbreviation is pronounced as the names of the individual letters. NASA and NATO are acronyms; IRS and UK are abbreviations. USA, pronounced Yoo-Ess-Ay, is an abbreviation. But in Hungary it's an acronym, pronounced OO-sha.)
People sometimes just make words up at random and if they sound good they may catch on: humongous, rambunctious.
But indeed scholars create words out of roots from other languages. Petroleum, from the Latin words for stone and oil. Telephone, from the Greek words for distance and sound. Sometimes laymen borrow suffixes or prefixes. After the launch of Sputnik, the first artificial satellite, it became cool to add -nik to words to taint them with hints of communism, like "peacenik."
And why is a word like fuck offensive? I can understand most other PC words [Cunt, nigger, etc] but why fuck and shit? As a teen, I and my friends use these two words quite regularly and normally, I dont get why they are so bad - they just mean sex and poop!
This goes back to an earlier era when people had manners. It was not polite to talk about sexual intercourse or bodily functions in public or in mixed company. So the words for sexual intercourse and bodily functions were considered rude. Both "fuck" and "shit" are venerable old Anglo-Saxon words with cognates throughout the Germanic branch of the Indo-European language family. The Germans say
Scheiß and the Danes say
skid.
But back to your original question. Slang comes and goes. The whole point of slang is to be clever and interesting. Once it becomes established it is neither of those things. So a slang word will either prove its usefulness and become established as an ordinary word, or it will fade away.
According to this . . . . the old Saxon word for vulva was pūse.
Indeed. As noted earlier, the original meaning was pocket or pouch.
We all seem to agree.