The phrase "flash out" is not used in standard English.
If you want to use it, it would have to be in an informal context, for example: "He flashed out of the room in a hurry".
A buried intensity can flash out for a second before going back undercover.
Then quick as a flash, out comes an apologetic little laugh.
These days certain killer words flash out instant red alerts: "reform", "flexible", "harmonise" and "modernise" all signify their opposites.
Soccer was my father's sport, and would be mine, but she liked to flash out into the yard and perform "the high trap".
The words flash out and then fade, like something from the cut-up prose of William S. Burroughs or the disjointed Americana of John Ashbery: "You won't be asked to leave, but you will want to leave".
But then there are the bright colours, the oranges, blues and greens that flash out from his work, which hardly fit with modernism's subfusc palette and pared-down aesthetic.
It felt buoying in private, but in public it flashed out in alarming ways.
"The lights flashed out, back on and then out again," he said after getting off the train at Grand Central Terminal.
It was even dangerous to be sitting in the front row when he flashed out his sword like Douglas Fairbanks".
As the team's head-brass flashed out on the turn The lovers disappeared into the wood.
Nobody handed out a single flyer or flashed out a Twitter feed or gave us something to take home and remind us what we were there for.
