Is "consarnit!" still current anywhere in the United States?

He said 'The sheriff is near!"

– Olson Johnson

This was more popular in days of yore, before Disney started sending out cease-and-desist notices to everyone who said that. (Or, alternatively, you could elect to pay royalties.)

Hoooly mackeral!

Some situations just don’t lend themselves to real profanity. Or cursing, even.

Once, when I was on a USCG cutter doing a fisheries inspection on a Russian trawler, I managed to spread the word around some shipmates that “Yob t’voyu maht!” was Russian for “Have a nice day!”

To answer Jerry Seinfeld above consarn is a dialectical form of the verb concern, which in the imperative mood can mean “confound!”.

From OED