Yup - but not only that, although Britain is pretty small, we have a huge number of regional accents so obviously everyone takes the piss out of everyone else. For example, although I have a fairly generic central Scottish accent at the moment, I was brought up in Orkney so my original accent would be understood by nobody on this board (with the probable exception of thinfourth), sometimes I speak like my father (fairly posh Warwickshire accent - that's pronounced Worrickshire) and sometimes like my mother (western Australian) so I tend to imitate other folks accents anyway.

South Park probably heightens the rest of the world's view of US accents. I'm sure they exaggerate them - or do they??