The Countries: Forget it, Burkina Faso, Michigan is still the worst.

[FadeToBlack&Gold]

Hungary's has long been my favorite one, because it sets the stage for just how impossible it is for outsiders to pronounce anything in that language at first glance, let alone learn the grammar.

 

[Kepler]

I remember Magyar Posta from my youth collecting.

Lying Swiss:

My youth specialization. I loved the name of this obsolete country and never dreamed it would be reborn and become world historical:

 

[Kepler]

These don’t really count because they aren’t truly endonyms

TIL. Thank you.

An endonym or autonym is a common, native name for a group of people, individual person, geographical place, language, or dialect, meaning that it is used inside a particular group or linguistic community to identify or designate themselves, their place of origin, or their language.

An exonym or xenonym is a foreign established, non-native name for a group of people, individual person, geographical place, language, or dialect, meaning that it is used primarily outside the particular place inhabited by the group or linguistic community. Exonyms exist not only for historico-geographical reasons but also in consideration of difficulties when pronouncing foreign words, or from non-systematic attempts at transcribing into a different writing system.

For instance, Deutschland is the endonym for the country that is also known by the exonyms Germany and Germania in English and Italian, respectively, Alemania and Allemagne in Spanish and French, respectively, Niemcy in Polish, and Saksa and Saksamaa in Finnish and Estonian, respectively.

The terms autonym, endonym, exonym and xenonym are formed by adding specific prefixes to the Greek root word ὄνομα (ónoma) 'name', from Proto-Indo-European *h₃nómn̥.
The prefixes added to these terms are also derived from Greek:

• endonym: ἔνδον (éndon) 'within';
• exonym: ἔξω (éxō) 'outside';
• autonym: αὐτός (autós) 'self'; and
• xenonym: ξένος (xénos) 'foreign'.

The terms autonym and xenonym also have different applications, thus leaving endonym and exonym as the preferred forms.

 

[St. Clown]

Endonym Map: World Map of Country Names in Their Local Languages

An endonym is the name for a place, site or location in the language of the people who live there. This map depicts endonyms of the countries of the world in their official or national languages.

endonymmap.com

This is sourced from the UN, each nation listed using its official name in its official/native language.