Photograph by Jason LaVeris/FilmMagic via Getty

The comedian Tig Notaro appeared on “Transparent” and hosts a

(http://professorblastoff.com/), but she is best known for a standup set she performed two years ago, a few days after learning that she had breast cancer.* She later got a double mastectomy, after which she chose not to have reconstructive surgery. Last night, she played The Town Hall. She told a story about receiving a pat-down at the airport, where the female security agent was obviously concerned that Notaro was in the wrong line. “She didn’t feel any boobs, and she didn’t feel a bra,” Notaro said. “She looked up at my face, really drank it in. Apparently that didn’t help.” (Notaro is queer and is interested in androgyny; her current standup tour is called “Boyish Girl Interrupted.”) “I knew all I had to do was talk,” Notaro said. “She’d hear my voice and she would know that I’m female. But I really didn’t want to help her_._”

Notaro was wearing a gray sports jacket, jeans, and a pink button-down shirt. She finished the bit and unbuttoned her jacket. From the back of the house, someone shouted “Whooo!”—a catcall, or a catcall in scare quotes.

Notaro, with one arm still in her jacket, looked surprised. “Did you not hear the story I was just telling?” she asked. She paused, letting a small wave of laughter roll over the crowd. (Anaheed Alani, of Rookie magazine, once wrote that Notaro “uses long pauses . . . better than probably any other comedian in the world.”)

“You know, it’s funny,” Notaro continued. “I was going to do this show with my shirt off, anyway. I’m about one more ‘Whooo’ away from going topless.” It was a joke, obviously. But, predictably, several whoops emerged from the crowd. Notaro made an instant calculation. Then she ripped her shirt open, Superman-like, and she was topless.

Long pause. She is a deadpan comedian of the driest vintage, and her face remained stolid. The patches of the audience that were stunned into silence alternated with the patches that were seized by deep, hoarse laughter, resulting in weird patterns of wave interference. Notaro is thin. She stood with her shoulders slightly hunched, her ribs visible, her lack of breasts visible, her surgery scars visible. “Naked onstage” is a classic premise for an anxiety dream, and the moment felt surreal. So it’s true that she doesn’t wear a bra. Is this being filmed? Is this actually happening?

After a few seconds, she arched her eyebrows in a schoolmarmish way, as if to say, Are we ready to go on? She performed the rest of her set, another twenty minutes or so, without covering up. She alluded to it once or twice—“You’re thinking, ‘When’s she gonna . . . ?’ She’s not gonna”—but mostly she stuck to her jokes, about “Yellow Submarine” and the phrase “That’s what she said.” She finished her set and received a standing ovation (which, in fairness, she had explicitly requested), and then she buttoned up her shirt, jumped down from the lip of the stage, and ran through the house toward the lobby.

Del Close, the guru of modern improv comedy, was known for imparting instructions that were halfway between koans and clichés. One was “Don’t Think.” Another was “Follow the Fear.” Notaro’s shirtless performance was a textbook illustration of what these phrases mean, and why they are good advice. If a bizarre series of escalated jokes suggests an opportunity to disrobe in public, the appropriate response is to think better of it, and to keep your clothes on. By not thinking and doing the inappropriate thing, Notaro, not for the first time, found within her joke-telling a moment of transcendence. The image was almost too easy to read as allegory: a comic literally willing to bare it all, her flesh literally scarred, the shape of her body a living rebuke to gender norms. Walking out of the theatre, I began to wonder whether it was a little too perfect. Had it all been planned? Then I bumped into Notaro, who seemed just as surprised and thrilled as her audience did.

_*Correction: A previous version of this post identified Notaro as a writer for “Inside Amy Schumer”; she no longer writes for the show. _