How do you prounce rhoshandiatellyneshiaunneveshenk koyaanisquatsiuth?

You're actually asking about a fictional name that was popularized in the 1990s. There is no correct pronunciation for "Rhoshandiatellyneshiaunneveshenk Koyaanisquatsiuth" because it's not a real name.

It was used as a humorous example of a ridiculously long and complicated name, often used to make a point about the absurdity of certain naming trends or the difficulty of pronouncing some names.

So, while you can try to sound it out phonetically, there's no official way to pronounce it. It's more of a joke than a real name!