Friend of mine, from northern Italy (Piedmont), puts it down to "bloody meridionali", but it's possible he might be ever so slightly biased :-).

Calling someone a "bloody...ahem meridionali" sounds a lot like those guys who would address a black guy as an "annoying N...nuisance, I mean".

Tell him he can drop the politically correct facade and call us Terroni (or Terun, with an hard-R), no need to pretend otherwise.