Dodgy
Mate I reckon it's the Brits, closely followed by the the Kiwi's and Oz
I think I'd agree, Dodgy, although I'm not sure whether to be or . We have so many local accents & dialects crammed in to our small islands, influenced by so many languages, that words & phrases just get absorbed into everyday use. New words are not a problem for me - they can enrich our language. It's the erosion of grammar that does the damage.
In my part of the country, the local "Geordie" dialect is almost a language unto itself. A mix of old Scots, English, and Norse (old Scandinavian) tongues, it's practically unintelligible to outsiders, unless moderated - which can be a source of some amusement to us. Other parts of the UK (Yorkshire, the West Country, etc.) have similar claims, and London's Cockney rhyming slang is well-known (despite the efforts of *** Van ***).
EDIT - Ah, I see the AutoProtect robot has been at work. I meant, of course, that fine actor, Mr Richard Van Water-Restraining-Earthwork.
And yes, friendly insults are (usually!) taken in the spirit intended.
Noo haddaway wi' ya barra, an' gan canny!