Whether you're a sitting U.S. president or a downtown arts center, the rules are simple: Do not mess with Ani DiFranco or Margaret Cho.

Comedian Cho and singer-songwriter DiFranco, alike in politics if not in style, brought their get-out-the-vote tour, pithily called "Vote Dammit!," to the Overture Center for the Arts for a sold-out show Tuesday night.

While Cho hilariously deboned and filleted right-wing bigots and DiFranco gave protest songs a 21st century twist, organizations like the Feminist Majority and Progressive Democrats were busy in the lobby registering audience members to vote and passing out literature.

But a visibly rankled DiFranco lit into Overture Center management during her 90-minute set for charging the activists a fee to set up their tables. She said it was the only venue on the 12-state tour to demand such a fee.

"This place decided to charge us per table," she said, as the crowd booed and hissed. "I don't know if there's a right-wing ideologue at the helm who doesn't like us talking to each other, or if it's just slimy corporate nickel-and-diming."

DiFranco stopped short of giving out theater management's e-mail address, but said she figured the audience was smart enough to find it on their own.

Well, the pristine Overture Center needed a little scuffing up, and Tuesday's rowdy, ribald, passionate show, the first since the nine-day opening celebration, broke it in nicely. Opening comedian Bruce Daniels made history as the first Overture performer to use the F word onstage (unless something happened at the Dave Brubeck concert I'm not aware of).

Not to be outdone, Cho used most every other swear word during her hourlong set, which had the audience laughing and cheering loudly throughout. Cho shaped much of her material around recent events, and she got in a couple of good lines about '70s soft-rock artist Cat Stevens - now known as Yusuf Islam - being apprehended by the Department of Homeland Security. "Free Cat Stevens!" she yelled. "Apparently they logged onto his Web site, where he was beheading Christopher Cross and issued a fatwa against Lionel Richie."

The New York Times recently said that Cho has some kind of Tourette's syndrome onstage, but that makes it sound like she spews out thoughts at random like a machine gunner. In fact, she's an expert marksman with her satire, drawing a bead on targets ranging from homophobes to Arnold Schwarzenegger to George W. Bush, and then letting the arrows fly.

Cho compared the weeklong tribute to Ronald Reagan to "Weekend at Bernie's," did a creditable Christiane Amanpour imitation, and came up with a brilliant way to force the country to accept gay marriage.

"All the wedding planners go on strike," Cho said. "• 'If we can't have a wedding, you can't have a wedding. Who needs a floral arrangement now?'• "

The diminutive but volcanic DiFranco delivered a sparkling 90-minute set, throwing herself fully into every song, whether it was an achingly lovely personal song like "Educated Guess" or an unapologetic political song, such as a new tune in which she lamented the new segregation of American cities like her hometown of Buffalo.

But the showstopper was the powerful poem "Grand Canyon," which began with DiFranco saying, "I love my country, by which I mean I am indebted joyfully to all the people throughout its history who have fought the government to make right."

DiFranco said she wandered around town before the show and was gladdened to hear so many people talking about getting involved in the election.

"It seems like your town got the memo," she said.