It’s time for the fascinating history of the word tarnation, which has nothing to do with the word nation

In 18th century America there was a trend of finding nicer ways to say curse words so they could shout exclamations without committing blasphemy. “Heck” and “gosh” originated at this time. “What in Sam Hill” was just a censored way of saying “What the hell?”

Damn and damnation became darn and darnation

At the time the word eternal was mostly associated with God and heaven, so the slang term “tarnal” was created to speak about eternity without invoking God

The new soft-curse word darnation sounded a bit like the slang word tarnal so people mashed them into tarnation (source)

“What in tarnation” means “What in eternal damnation” which also means “What the hell” which also means “What in Sam Hill” thanks to a bunch of Americans in the 1700s wanting to say bad words without incurring the Lord’s wrath