I am curious where you got this impression. Although there are localized insults/profanity, new variations rise to the surface constantly. Profanity in English tends to be on the front line of change in the fluidity of language. Sure, there are tried-and-true stand-bys, but there are always new variations entering the lexicon, even if only briefly.

This. I can guarantee you words like (if you'll pardon my French) "peniswrinkle" have never made it into American media that have reached the shores of fair England. IT just takes about three seconds of perusal on urbandictionary.com to see the variety of profanity that Americans come up with (you can tell it's Americans by the way certain words in the definitions are spelled).

I am not sure what you are saying here. Just because "peniswrinkle" is not in the American vernacular does not mean the American vernacular is plain.

That being said, I really enjoy listening to interviews with Russel Brand as he uses the English language in ways that I don't, so it is really interesting.

I feel Scots English is similar to American English, in that a lot of words are different. I think Scots English has its share of course language, that English down south (as Scotland is above England, for those uneducated in Geography) doesn't.

No, my point is that "peniswrinkle" is in the American vernacular, and it's an example of how American vernacular is not plain, but the fact that this word never makes it into a show like Seinfeld (which is then exported to Britain) is why people think American slang is boring.

Are we talking about Lowlands Scots or Scottish English? I draw a line between them, and consider Scots a different language (and I'm not confusing Lowland Scots with Gaidhlig here).

It's a term I have never heard before, but there are all kinds of dialects and local slang terms in the US. I remember "penis breath" got into E.T. back in the 80s.

It is interesting you mention Seinfeld, at it was a source of many quotable slang terms... like "yada yada yada," "johnson rod," "sponge-worthy," "shrinkage," etc.

LOL.. shrinkage.

I've never heard of this word "peniswrinkle"
and i do not consider it a real curse word, nor apart of American english for that matter.
UrbanDictionary.com is not the place to look for real words,
it's a site anyone can go on and make up words and their definitions for those words (and names).
I'm pretty sure people around the world (not just Americans) make up obscene words (though i could be wrong) .

A sort of generalisation of the two. I'm perhaps thinking more of what's spoken in Glasgow though. Just seems altogether more different. Although usually its just changing vowels, or apostraphy's (Don't know how thats spelt) E.g. Don't & Can't become Dinnae & Cannae. Head & Hand become Heid & Haund. Half an Hour becomes Haulf an Oor. I'd go into cursive but only if I was sure not to be banned.