Sacred cows get a spanking in two, violent new comedies, both from Scottish companies, at the Brits Off Broadway Festival, now in full swing at 59E59. “The People Next Door” from the Traverse Theatre, and the one-man-in-drag-show “Sisters, Such Devoted Sisters” keep their audiences laughing all while sneaking the rug out. They require careful attention – some of the accents are thicker than a pudding in a freezer. But listen keenly, and they deliver a lingering chill.

Henry Adam’s “The People Next Door” gives us a new Harlequin for the post-postmodern millennium. Ensconced in his council flat, Nigel (Ronny Jhutti) wears the motley of a gangsta, talks like a Rasta, is actually half-Pakistani, and can barely open a can of soup. Nigel, who would rather we call him Salif, is all wanna-be. Content to live on the dole forever, he pretends to toughness while quaking before the tidy Scottish biddy upstairs. He talks large while making himself very, very small.

Not too small to be noticed by the cops, however. Nigel’s half-brother has mixed himself up in terrorism, and Phil (Mark McDonnell), an apoplectic bobby, thinks he can use Nigel to solve the case. Phil scares the pants off Nigel – one moment Phil is smoking up his heroin stash, the next he’s beating his face into the carpet.

Persuading Nigel to go undercover at his brother’s mosque backfires on the cop soon enough, though. Finding new reserves of compassion in his reading (he’s not sure if it’s the Koran or not, because his version starts with a “Q”), Nigel starts to forge a little family out of his misfit neighbors, and families will fight to protect their own.

Comedy depends heavily on audience response – and on a Saturday afternoon, the large majority of the theatergoers were puzzled and quiet. Mr. Jhutti’s adorable Jamaican-by-way-of-Scottish accent wasn’t exactly an open book to some attendees, and references to rapper Notorious B.I.G. whizzed over a lot of heads.

Mr. Adam plays a tricky game, using police brutality as physical comedy and turning paranoia and racism into punchlines. He has judged the mix of critique and humor well, but only occasionally got the laughs it deserved. Admittedly, he doesn’t make things easy on his audience, overwriting some sequences. Long scenes with the batty Mrs. Mac (Mary McCusker) slow momentum perilously – and a two-and-a-half-hour running time is no joke.

The production tries desperately to move that time along. Director Ian Grieve packs the time with surprise explosions and nearly constant agitation, and Mr. Jhutti seems about to jump out of his skin with haste. Luckily, Miriam Buether’s impressive set gives him lots of places to rush about – a picture-perfect hallway outside his flat, as well as its grotty interior. Just like Nigel’s sad little apartment, though, the show is only as good as its inhabitants. Without an audience full of fellow-feeling, these comedians are playing one heck of a tough room.

***

Just down the hall, Russell Barr, far better at winding us ’round his press-on-nailed finger, doesn’t let his audience dictate the terms. His “Sisters, Such Devoted Sisters” rewrites the rules of what you can talk about and still seem like a lady. He straddles a stool, dressed to the nines in eight-inch heels and a peekaboo dress. He’s got a sadistic edge: Childhood reminiscences involve exploding pigeons and a homicidal crowd of Jack Russell terriers. But despite his stand-up ready cleverness and his irresistible humor, Mr. Barr is tricking us into enjoying tales of incredible horror.

Glasgow has four times more AA meetings per person than towns of comparable size, and everyone in Mr. Barr’s life has some sort of trouble with drink. He and his friends – drag queens and shoplifters – exist either tranquilized on drugs or hopped-up on violence. The wigs and the Versace pants conceal an amazing well of destruction, and rescue doesn’t seem likely from the aunts and uncles, mothers and dads who have long ago trapped themselves in the same cycles.

Mr. Barr only shudders occasionally, though. His tea-drinking always readies him for another funny story or two. In the tiny theater, he kicked his heels in our faces and occasionally sat in our laps. But he never outwore his welcome. An astonishing comic talent teetering on a pitch-black void, Mr. Barr is one Sister you should welcome into the family.

“The People Next Door” until May 22; “Sisters, Such Devoted Sisters” until May 15 (59 E. 59th Street, between Park and Madison Avenues, 212-279-4200).