Ever wonder what would happen if a bunch of sleep-deprived dramatists came together in a marathon session of writing with the express purpose of creating a half-dozen shows for next-day production?

Well, Thieves Theater - a radical cadre of theater artists based in New York, but currently in residence in the upstairs space at Theater Double, 1619 Walnut St. - dares you to come find out.

They call the concept "Fly by Night," and in a nutshell it's six writers, six directors and 18 actors with only 24 hours to come up with a play for an 8 p.m. curtain the following day.

Here's how it works: At 10 p.m. on Friday, each actor brings in one prop for the prop pool, and each writer is given one noun and one verb, a cast makeup (e.g., 1 man, 2 women), and 12 hours to complete a 10-minute script (about 12 pages). At 10 a.m. the following morning, each director picks a script and their cast - chosen blindly from the pool of actors - and gets 45 minutes rehearsal time on stage.

At 5 p.m., the individual productions get 20 minutes with the tech director to run lights and sound. At 8 p.m. - it's showtime!

Tickets for the evening's follies - every play goes up, no matter what - are $12 (students, $8). Call 215-557-9421 for more info.

Also at Theatre Double - having been extended through May 31 - is the classic "for colored girls who have considered suicide/when the rainbow is enuf."

Director Michael LeLand's intergenerational cast features local actors Juanita Amonitti, Shelita Birchett, Jennifer Bragg, Meryl Lynn Brown, Angel Hardy, Salama Shani and Veronica Wathome. Curtain: 8 p.m. Thursday-Saturday, 4 p.m. Sunday. Tickets: $18 & $20.

Home grown

1812 Productions is at it again, bringing its quirky brand of humor to the fore in "The Great Northeast," previewing tomorrow through Tuesday, and running through May 6 at the Adrienne, 2030 Sansom St.

Pete Kimchuk's black comedy - about the Northeast (finally?) seceding from the rest of Philadelphia - is directed by Pete Pryor and features an ensemble cast, including funny woman Jilline Ringle, of "Mondo Mangia" fame. Curtain is at 8 p.m. Tuesday, Friday & Saturday, 2 p.m. Sunday, 6:30 p.m. Wednesday. Tickets are $10-$20. Info: 215-592-9560.

International flair

East meets West in "The Silver River," a new musical theater work opening at 8 p.m. Saturday at the Prince Music Theater, 1412 Chestnut St., and continuing through April 15.

Depicting the Chinese myth of the forbidden love between the Goddess Weaver and a mortal cowherd, the production blends theater with both Western and Chinese opera, and musical idioms from both cultures created by a chamber ensemble of flute, cello, clarinet, violin and pipa - a four-stringed Chinese instrument similar to the lute.

Directed by Ong Keng Sen, "The Silver River" brings together the phenomenal talents of Tony and Drama Desk award-winning librettist David Henry Hwang, composer Bright Sheng and choreographer Muna Tseng. It is the Prince's first international production, involving artists from different parts of the Chinese diaspora.

Curtain: 8 p.m. Thursday-Saturday, 3 p.m. Sunday, 2 and 7 p.m. Wednesday, April 11. Tickets: $30 & $35. Info: 215-569-9700.