Yes, our humour IS different...
Little Britain is a facet of british Humour, same goes for monty Python, Fawlty Towers, The Office, or even at the other end of the spectrum Yes Minister (roughly UK version of the west wing, made about 20 years ago and god it's the funniest comedy I have ever seen...)

Yes, people in Britain wll insult you, or touch nerves and expect you not to flinch. Their being brutally honest and making a joke out of it, or being ironic or sarcastic, which is good. It's only not good when they go that step to far, which occasionally they do, but otherwise it's just being honest enough to say what your thinking and express it.

That said, there's the brutal waspish jokes and then there's just being rude. It's an invsible line which people only recognise after a while, it doens't translate well over the internet because you can usually tell if it' a joke or not by seeing the look on their face, the expression in their voice, whatever...


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On the initial post; the "Aren't you," is probably just an expression that's used all the time and comes as habit. The joke was, "You're quite the idiot," which was probably just pointing out they'd said something stupid...
That ISNT British Humour, but it is the bedrock British Humour is based on.