THE FUNNY THING about the Video Pirates, possibly this town's most screwball comedy duo since either the Joy Boys or Nixon-Agnew, is that nobody ever asks whether they're for real. It's like, uh-huh, you're pirates and you do funny songs and skits and some great cartoon and TV- rerun voice impersonations, and so, okay -- is that gun real?

"Yep, they always ask about the gun," says Mike Rosson, 28, a former unfulfilled post office worker who gave up the pension plan two years ago to seek fame as Captain Cable -- the one with the braids in his beard and a .45-caliber muzzle-loading cap-and-ball pistol in his belt.

The pistol, it turns out, is for real (though it has been deactivated to avoid the kind of trouble the Pirates once had with a humor-impaired security guard at the District Building). But the Pirates are for real, too. And recently they've actually been making some money -- working comedy clubs, private parties and promotions, the latter two largely through Celebrations Unlimited, a local talent agency.

"Arrh," Rosson growls sheepishly. 'We're just a couple of scurvy bilge rats from Riverdale."

Captain Cable and his mate, Skinbeard -- alias Mark Frederick, 29, the one with the eye patch and striped stockings -- put together their first stage act in the car on the way to an open mike at Eskimo Nell's, the former comedy venue in Arlington. Rosson was going to do the act alone -- he had these funny songs, including the Pirates theme ("Yo-ho, yo-ho, the vid-e-o," and so forth) and another lament against overcommercialization called "Popeye Sings the Blues." He and Frederick just decided to do something together; they wore scarves with their street clothes.

Rosson and Frederick met at Parkdale High about 12 years ago, and have been friends and casual collaborators since. After that first Eskimo Nell's date, the Pirates spent their next eight months mostly at open-mike nights, working up what is now an hour and a half's worth of principally television-inspired sketches and songs. Their first paying job came last summer at a club in Frederick, Maryland.

The Pirates' strongest points are their elastic voices: between them, they say, they have 250 characters. Rosson does a peerless Magoo ("We have a lot in common," he says, tilting up his extra-thick glasses). And the Pirates' funniest sketch -- "Don Knotts' Landing" -- pivots on Rosson's hilarious mimicry of Barney Fife and Floyd the barber.

For Frederick, the old Joy Boys -- longtime Washington radio partners Willard Scott and Ed Walker -- "were kind of my afternoon babysitters when I was growing up," and they rank up there in his idol list with Mel Blanc. And Frederick's cartoon voices are as close to Blanc's as you will hear.

In any case, the Pirates are busy. They're working with the Pheromones on a video of that duo's satirical single "Yuppiedrone"; they're putting together a series of celebrity phone- message tapes, and, through Celebrations, are often called upon to deliver "scurvygrams."

And one afternoon last week, Rosson was seen on M Street downtown, handing out promotional leaflets for a new bar. A shirtless sidewalk-dweller ambled up to him, smiling. "Howyadoin'," the fellow said, and glanced down at Rosson's belt. "Is that thing real?"