Hawaii Congressional Candidate Knocked Out Cold During Beach Fight, On Video

A Hawaiian congressional candidate got hit by a double whammy ... he first got his ass whooped on the beach ... and then he reportedly got arrested for making terroristic threats ... and the brawl is on video.

Kirill Basin, a Democratic candidate running for Congress against incumbent Democrat Jill Tokuda, got into a heated back-and-forth Saturday with a couple at Keawakapu Beach on Maui. The verbal altercation was captured by a witness on dramatic video, along with the ensuing ass-kicking.

Check it out and bring the popcorn ... the clip starts with Basin talking about putting the other man in the hospital before doing a total 180 and shaking the man's hand.

But then Basin tells the man's female companion to go f*** herself -- and that's when everything goes off the rails.

In the end, Basin gets knocked out cold by a single punch thrown by the other man. The politician drops like a sack of potatoes, and some guy starts slapping his face to wake him up while he's unconscious on the ground.

After cops arrived, things only got worse for Basin, who was arrested for allegedly making terrorist threats ... and his bail was set at $1 million -- according to the Civil Beat.

The news site reports a 61-year-old man asked Basin to turn down the volume on the music he was playing. Basin allegedly implied he had a gun and would shoot his wife, sparking the physical altercation.