You open yourself up to an obvious jab when you call your holiday revue "dysfunctional," and I was all set to take advantage of the invitation at the apparent end of Wednesday's opening Second City performance -- when, what to my wondering eyes should appear but a really funny ad-on, an improvised musical, "Frogs in Love," that made the evening worthwhile.

Some people left at that point, thinking the evening over and probably glad of it. Too bad. Actually, I thought the audience suggestion was "Broads in Love," but I'm glad the six-person troupe heard it the way they did, because the result was a 20-minute foray into uncharted absurdity that offered all the funny personality and inventive surprise of which good improv is capable.

		"The Second City Dysfunctional Holiday Revue" Where: At Public Theater, O'Reilly Theater, 621 Penn Ave., Downtown. When: 8 tonight; 7 and 10 p.m. tomorrow. Tickets: $25 to $45; 412-316-1600.

Before then, there was just too much stale sketch comedy. I say "was" because maybe the troupe is quick enough on its feet to jettison some of the nonstarters. My own recommendations for the delete key would be the ethics-challenged senator, the skit about homelessness and the two gay guys. Actually, that last is so repellent it's almost special. If you also threw out the over-worked, one-joke sketch about the PC nativity story, you could get the two acts down to one and use the improv as Act 2.

And they should embrace success when it comes. When the frog musical was greeted with sustained applause, they could have ended on that high, instead of adding a comparatively uninspired round of freeze-tag.

Of course improv is risky, but audiences know that -- it enlists us on the performers' side, so we forgive the misfires and love the successes. Sketch comedy, though, even when we can see its roots in improv, better be funny. Too many sketches felt tired and passe. More to the point, the performers didn't seem to be personally invested in them, as though they were giving us a photocopy of a photocopy of a photocopy.

Some sketches are fine -- the global warming make-out, God in the bookstore, the letter to Santa, maybe a few others, depending on your taste. Some are OK. Some are brightened with elements of improv, and there are brief black-out bits that show wit.

"Holiday" may be misleading -- only about a third is related to the season. They're boned up on Pittsburgh references and work them in when possible, to the cheers of the audience. But this eventually turns into outright condescension in a whole number praising Pittsburgh landmarks, as though we were rubes eager to have visitors tell us we're great.

Well, sure, we are ... Still, I think the audience response to this pandering was just because it was better than the other stuff.

It's like the opening, in which they burst on stage full of fake enthusiasm, pumping us up as if we were some TV audience.

These performers deserve better. The leader in invention and variety is Brendan Jennings, who is fully ready for prime time. Dana Quercioli is deliciously quirky and, being from Cleveland, has a good start on speaking Pittsburgh. She is also a quick reincorporator, keeping a joke alive, as is Rebecca Hanson, who played a great frog lover.

Tim Balz and Mary Sohn also have their funny moments, and I hope it's not Hans Holsen's fault that he is featured in most of the lamest sketches.

The point is that all six rose to the occasion in the improv, as though they were free at last to show their chops. That set us free, too.