DEVIL WITH THE BLUE DRESS ON For a moment, Hart and Chase hide their teeth.

Some audience members come to Shells’s cabaret act after reading misinformation in newspaper listings about a young JPMorgan Chase analyst who’s gotten the gumption to sing piano-accompanied standards. “We get more press as ‘Michelle Haylie Hoffman sings blah blah blah,’_” explains Roslyn Hart, who plays the character she created with fellow comedian Nick Chase. Their third major production, Shells—InFamous, takes place Sunday 25 at Joe’s Pub.

After listening to Shells rant about her vapid Sex and the City–wanna-be lifestyle and embarrassing dating adventures—which are interrupted by incongruous songs and copious amounts of shiraz—most of those clueless audience members figure out the gag. But there are always a few who remain in the dark. Because, even though Shells is not an actual person, she’s heartbreakingly real. “People see themselves in the show,” Chase says. “Then they come up to us and go, [Sarcastically] ‘Thanks a lot!’ We’re like, ‘It wasn’t based on you…and why would you admit that?!?’”

Neither, however, was Shells born in a vacuum. Chase and Hart, who’ve been best friends since ninth grade in Odessa, Florida, waited tables together in the early aughts at Bryant Park Grill. “That place is a magnet for the businessy, young, cruisin’-for-a-husband type,” Chase says. Hart adds, “Yeah: mojitos, Manolos.”

At the time, the duo performed sketch comedy as Bros Before Hoes. They started eavesdropping on their customers and Shells was born. Some bits of dialogue were swiped verbatim. “Remember that girl,” Hart asks Chase, “who said, ‘I’m not racist, it’s just that people have their preferences and I don’t prefer them’? Shells just says Mexicans instead of them.” Other bits of Shellsian wisdom include, “Buddhism is like a tennis bracelet: It goes with everything” (on mixing religions), and “I make out with girls, but she does it when no hot guys are around” (on her lesbian sister).The character was initially filler—the duo shot videos of her (now on YouTube) to screen during costume changes. But audiences demanded more. Enter the cult of Shells.

Both previous Joe’s Pub shows sold out. And the crowds—men and women, gay and straight—are vocal. The major story line running through each all-new performance is Shells’s obsession with a man named Scott, whom she believes to be her soul mate. They went on one date. Even though Scott has repeatedly asked her to stop contacting him, some twist of cellular-technology fate inevitably brings him back into her life—while she’s onstage. This is when audience members start shouting, “Don’t text him, Shells! He’s all wrong for you!” Or, alternately, “Do it, Shells! Do it!!!”

Granted, these participants are in on the joke—which makes it all the more interesting. “I have a friend who says, ‘I love it because it gives me a chance to yell at myself, to tell myself, Don’t text him!’_” explains Chase. “Everyone has a Scott they’re hung up on.”

Chase and Hart respond by testing the boundaries of their fans’ adoration. In the last show, in February, Shells flirted with a guy in the front row and insulted his date. About an hour later, she gave him a tiny striptease. Then she spit a cherry in the girl’s face. “When Shells gets drunk,” explains Hart, who hadn’t planned the cherry bit, “her id comes out.” The couple left the theater; the crowd freaked; Shells had to fumble to win it back. In reality, the man and woman were plants, but Hart never revealed the truth. Even the duo’s close friends fell for the stunt.

So imagine how confusing it is for the poor, foolish men who solicit Shells on MySpace. “They’ll message to say, ‘Scott just doesn’t understand you.… You’re a sweet girl.… I’ve been hurt before too,’_” Hart says. Naturally, Shells invites the guys to her show, where they’ll arrive to discover a despicable, self-destructive girl to whom they’ll inexplicably still be attracted and for whom they’ll somehow still root.

Shells—InFamous happens Sunday, May 25 at Joe’s Pub.