In the annals of the Most Disastrous Shows Ever, there is a new entry. Folk-rock singer Michelle Shocked had the plug pulled on her concert Sunday night after launching into an anti-gay-marriage speech that led most of the audience to walk out.

Did we mention that her fans largely lean well to the left, thanks to the liberal politics that previously infused much of her music, and that the gig where she chose to come out (so to speak) as an Old Testament-citing preacher on homosexual issues was in the heart of San Francisco?

Word of the debacle began spreading via social media even before the operator of Yoshi's interrupted Shocked's performance to announce that, as a gay man, he could not allow the show to continue and she would have to leave the stage. Ironically, Shocked had spent much of the show asking the crowd to engage with her and even pick her set list via Twitter. It's unclear whether she had any idea that, within hours, outraged former fans would be using that same forum to declare that they believe her career is over.

From all accounts, the first set had gone great, but when Shocked returned for the second set, she began talking about the evils that will result if California's Proposition 8 is overturned by the courts, to allow gay marriage in the state. Shocked cited verses from the Old Testament condemning homosexuality, first in English and then, puzzlingly, in Spanish. She even told the crowd that they "could go on Twitter and say 'Michelle Shocked says God hates f--s'," although that particular line was interpreted differently by some on hand, as either ironic or completely sincere.

The tweets that came from her account during the Yoshi's show were actually made by a patron named Matt Penfield, who'd been invited up during the uneventful first set to act as Shocked's Twitter intermediary. When things started to go very badly in the second set, Penfield not only left the stage but exited the auditorium to mill in the lobby with other confused and outraged fans who were trying to make sense of what had just happened.

"It was a very painful experience to go through," Penfield told Yahoo! Music. He not only sat on stage with Shocked for most of the show but visited with her backstage during the break. "To be that close to someone who is clearly having a breakdown of some sort is not an emotionally comfortable place to be. I'm still a little bit shaken up. And I don't like to see people vilified"—as he's well aware Shocked is being today. "I still love her music and I'm not going to delete her from my playlist or go smash CDs. But if she has made a conscious decision that she is going to use the stage to espouse beliefs that are hateful and damage groups of people, she probably should not be charging money for a concert. If she wants to sit on a panel at a conference or go to a religious festival, I think in that context she should say whatever she wants. But I do think that doing it as a bait-and-switch at a concert performance is really unfair and not showing respect to people."

Penfield said he was shocked—yes—when Shocked began talking about homosexuality, but that in retrospect, he thinks that her doing this specifically in San Francisco was planned and not spontaneous. Perhaps the always brash singer/songwriter believed she was speaking truth to power by boldly coming out against homosexuality in the heart of the gay community?

Mind you, this is a performer who once started a video by spray-painting an anarchy symbol on a sidewalk... whose most famous album cover shows her being held by police in a chokehold... who has spoken out against George W. Bush and other Republicans as forcefully as Steve Earle or any other avowedly liberal singer... and who was recently arrested at an Occupy protest.