DOCTOR NIGHTLIFE figures that if you patronize Bushmill's long enough, you develop Irish blood; why do you think they call a shotglass a jigger, anyway? Ireland's premiere traditionalists, the Chieftains, make their semiannual whirl through Wolf Trap Friday ($20 reserved seats, $12 lawn tickets; 255-1860 or 432-0200). Elsewhere: FRIDAY

K. T. BAR THE DOOR --

It's almost a shame that K. T. Oslin's "80's Ladies" was such a monster success -- it almost makes her sound outdated already. But Oslin (only in the South could any mother name a child Toinette) is as feisty a modern woman as could be desired. The other hook you hear about Oslin is that she writes "characters," which is usually a not-too-subtle Music Row dig at her years in the New York theater and Jingle Alley districts. But for a better idea of her songwriting style, look back to her very first folk-singing partnership -- Houston, 1962, Guy Glark. Character, indeed. K. T. Oslin performs at the Kennedy Center Concert Hall ($18 to $22.50, $6 obstructed; 467-4600).

PERFORMANCE WHAT AM --

The musical/satirical/terpsichorean/would-be lounge lizardly Art Club troupe, which was named "outstanding guest company" at the Source Theatre's 10th local theater awards this week, shows off its newest genre invention -- the "neo-quasi operetta" -- Fridays at 7:30 through the rest of the month at d.c. space ($8 plus $5 minimum; 347-1445 or 797-1304). "Dinner Party What Am" and "The Archeological Picnic" detail the adventures of two couples, Skitch and Esperanta Parker and Roy and Gladys Benny; the Bennys' surrogate son, a ventriloquist's dummy; the Parkers' tap-dancing maid; Cleopatra's mummy and a lotta white bread. You just hafta be there.

WHAT'VE FLU DONE FOR ME LATELY? --

Janet Jackson's 1814 Rhythm Nation tour, suspended last weekend after she fell victim to a viral infection in St. Louis, is scheduled to kick-start again at Capital Centre Friday, Saturday and Monday, with seats available for all three shows ($22.75; 432-0200).

THE NAME PAIN --

Doctor Nightlife would probably ride out to hear Goin' Goin' Gone jittering for the dance crowd at Cherry Hill Park if it didn't start that stupid Billy Joe Royal song running around in her head. Dance workshop at 7, concert 8 to 11 ($8; 530-8515). Take the Beltway to Route 1 south, turn almost immediately right onto Cherry Hill Road and drive a mile. SATURDAY

THE NAME'S A FEIGN --

Take Chris O'Connell out of Asleep at the Wheel, and Maryann Price from Dan Hicks and his Hot Licks, dress 'em up with some retro-Cline accoutrements and a dose of Ellington class and you have the sassiest "sister act" ever to sashay out of Austin: The pseudonymous Ethyl 'n' Methyl hit the happy tour trails at d.c. space on Thursday ($8; 347-1445) and the King of France Tavern in Annapolis all next weekend, Aug. 17-19 ($7 to $10; 301/263-2641).

THE NAME REMAINS THE SAME --

Tom and Steve Chapin have a lot of the same interests their brother Harry did: Both write and record modern traditional music; both are involved in family-oriented, ETV-type projects; and both are on the board of directors of the World Hunger Year (WHY) organization founded by their brother. Tom and Steve are also touring in tandem with "A Tribute to Harry Chapin," a sort of live "WOLD" program, Saturday at Baltimore's Pier Six ($18 reserved, $9 lawn seats; 800/638-2444 or 301/625-1400) and Sunday at the Birchmere ($15; 549-5919 or 800/448-9009). SUNDAY

THE NAME IS SPAIN IS NOT SO PLAIN --

It may not be a household name, and it's sometimes mistaken for Japanese, but Yomo Toro is a household face to anybody under the age of 12 -- he's a "Sesame Street" staple both in front of and behind the cameras. Toro, who is actually Puerto Rican by birth, is the reigning king of the mandolin-like cuatro, a descendent of medieval Spanish string instruments, and that's no left-handed compliment: Toro secretly taught himself to play his father's cuatro when he was only 7, but being left-handed, he worked it out upside-down, and he still plays that way. On the adult side, he has scored several movies and recorded with the likes of Willie Colon, Rito Puente and Reuben Blades. Toro's ensemble performs at the Museum of Natural History's Baird Auditorium ($16, students with ID $8; 357-3030).

THE NAME IS GAMEY --

The Bayou triple-bill of Murder Ink, Silence and Cut Throat is an all-ages show. Just in case you couldn't tell ($5; 333-2897). TUESDAY

THE NAME IS TOO LONG --

The "Buy Me, Bring Me, Take Me, Don't Mess My Hair: Or, Life According to Four Bitchen' Babes" tour (gasp) is another of Christine Lavin's femininst songwriter's traveling conventions, this editions showcasing Lavin, Megan McDonough, Sally Fingerett and the underestimated Patty Larkin (Tuesday and Wednesday at the Birchmere; $15, 432-0200). THURSDAY

SANTANA-RAMA --

One thing you have to say about Carlos Santana: He doesn't change his tune to fit the fashion. His new album, "Spirits Dancing in the Flesh," is dedicated to labor cult figure Cesar Chavez; it features guest shots from Vernon Reid, Wayne Shorter and Bobby Womack, and includes covers of Curtis Mayfield and the Isley Brothers (at Merriweather Post, pavilion seats $20, lawn tickets $15; 800/543-3041.