An (Upper-)Bavarian would for example never say "die Butter". It is and will always be "der Butter". Same with "der Radio" in the South and "das Radio" for the rest of the country.
Another funny thing I stumble upon every time Oktoberfest starts: Oktoberfest in Munich is referred to as "die Wiesn" (the lawn/grassland). Bavarians don't know an 'e' in the end of a noun, they will therefore always replace it with a 'n'. In the rest of Germany, Wiesn doesn't exist. It's either 'Wiese'(sgl, a single grassland) or 'Wiesen' (pl, many grasslands). Since Wiesen sounds more similar to 'Wiesn' than 'Wiese', even newspapers regularly refer to the Oktoberfest as a multiple of 'Wiese' which - for us - sounds just wrong: "Heute sind wir auf den Wiesn gewesen".