Pinzutu means "sharped". Some people say that it used to describe the hats
of the Louis XV's soldiers when they invaded Corsica. For others, it is about the effect
that the “people from the north” have on “people from the south”: they clench their lips
and close the vowels when they speak, so their mouths are sharped.

Anyway, like the majority of nicknames concerning a community or a nationality,
it is pejorative.