"It's 50 percent uncertainty and 100 percent entertainment value," the master of ceremonies tells the audience at the Round House Theatre's "The Club Etcetera."

It would be nearer the truth to reverse those figures. "The Club Etcetera" is a slapdash summer grab bag of impromptu comedy sketches, dance, mime and music strung together in the format of a 1930s nightclub show. The program changes with the whim and inspiration of the performers on stage.

The result is an erratic evening of entertainment. A little gem -- Jerry Whidden and Michael Littman in a mime scene between a janitor and a robot -- sparkles amid sketches that stumble over unimspired pratfalls. Betty Clark can belt our a big-mama song with zest. Then black humor slips into questionable taste in another sketch.

When you add it all up, the entertainment value tips in favor of "The Club Etcetera." The young and high-spirited performers are having fun, and it's infectious.

As Chef Bruno, David DiGiannantonio whips up a mess extraordinaire with a meat-loaf sandwich. In the poet's corner, Littman recites a poem about garbage. Mark Jasper and Gayle Behrman are marvelously funny in a sight gag acted out behind a screen. A game show titled "Name That Neurosis" doesn't come off, but "The Improv Commandos" does work. Michael Higgins has his funny moments as the stand-up comedian and master of ceremonies but suffers from overexposure.

It's pot luck with such an off-the-wall production. That's part of the fun.

Tom Schall, Tucker Ewing and Brooke Levinson are among the energetic performers. "Scat Man Norman & His Really Neat Band" -- Brian Bennett on the keyboard, Robert Martin on guitar and strings, and Chris Patton on saxophone and horns set a brisk tempo for all the goings-on on the stage.

"The Club Etcetera" is dark on July 17 but resumes performances July 24 and 31 and Aug. 7 and 14. The theater is at 12210 Bushey Dr., Silver Spring.