I've just seen this thread, whilst looking for another one, and it reminded me that there was something I meant to write on here a month or two ago.
I was on the open-topped bus going home from Bournemouth. I was the only local person upstairs, all the rest were grockles. I heard two of them talking, saying that they were worried they wouldn't be able to undestand the local accent when they got to the holiday park in Swanage, and that they were also concerned whether there would be 'mod cons', such as Internet access, available out here in the sticks.
Their conversation continued, and it was obvious that they thought the Dorset population consisted solely of farm labourers with no education and low IQs. I was feeling annoyed and amused in equal measure.
Then I heard them talking about where their stop was. One of them tapped me on the shoulder, saying, in the type of voice that people use to talk to foreigners, "Excuse me, do you know where Rempstone Road is?"
I made a snap decision to reply in a really strong Dorset accent, and I talked to them for a while, saying things like "ah" and "yer tiz" as much as possible. They didn't seem to think anything was amiss.
Then my mobile rang, and I answered it, talking in my normal, non-Dorset voice. After I'd hung up, it took me a while to work out why they were look at me in confusion. Luckily, we were approaching my stop, so I got up and left quickly.