Most of my family in France come from the east, very near Alsace - this was and still is very traditional French humour and much enjoyed in the region itself, especially as the Alsace accent is quite special ! Similar is done with other regional accents and quirks.

Fortunately the French in general are far less precious about such matters - their assessment of it is much more dependent on whether hurt or fun is intended, rather than offence for the sake of offence.

Vive la France et les Français !