On a recent evening, the two men were upstairs having old-age spackle applied by Annamarie Tendler Mulaney, the show’s makeup artist and Mr. Mulaney’s wife. They were excited for the show as their guest, Matthew Broderick, is a particular hero of Mr. Mulaney’s. But they were also nervous.
Mr. Mulaney had food poisoning after last night’s dinner. He’d spent a lot of the morning sick and had gagged during the tuna segment of the matinee. As Mr. Mulaney sat spooning applesauce from a souvenir mug (the heartless Mr. Kroll was downing chocolate-dipped macaroons), he discovered that even discussing tuna required intestinal fortitude. But he soldiered on.
The origins of “Too Much Tuna” involve a lunch with the writer Jessi Klein and an overburdened salade niçoise, though the two men soon decided the foodstuff was a lot funnier in sandwich form.
“There’s something humiliating about tuna salad,” Mr. Kroll explained.
Mr. Mulaney worries less about guests eating the sandwich now that he has learned that panko, used as a binder, is a bread crumb mix and not a building material. But both men still feel anxious about anyone eating a fish sandwich that has sat for an hour near hot stage lights.
While they were touring the show, Bill Hader once took a huge bite and spat it into Mr. Kroll’s mouth. Jimmy Kimmel lobbed a ball of it into the audience where it hit a woman with a seafood allergy. She didn’t find this funny. It was anyone’s guess what Mr. Broderick might do.
With wigs, microphones and age spots firmly in place, Mr. Mulaney and Mr. Kroll found him in a backstage holding pen. Mr. Kroll offered him a Clamato, but Mr. Broderick, dapper in a sweater in competing shades of charcoal, politely declined.
They spent 15 minutes chatting on topics that would make it to the onstage interview (Mr. Broderick’s vomiting during a production of “Biloxi Blues”) and others that wouldn’t (why he hadn’t declawed his cat).
Mr. Kroll said that if Mr. Mulaney had to run offstage to upchuck, they would use the code: He has to feed the meter.
“It’s fine,” Mr. Kroll said. “Gil will just talk to the crowd.”
Mr. Broderick deadpanned: “You have so little respect for the money the audience has spent.” He mentioned that he’d caught past episodes of “Too Much Tuna” online and pronounced a few words in the strange, vowel-eliding style of Faizon and St. Geegland: “Br’dway,” “c’caine.”
Mr. Kroll told him not to worry about the interview: “It’s on us to make it entertaining.”
Mr. Broderick didn’t seem entirely convinced. “This is gonna not work,” he said.
Mr. Mulaney replied: “I have fears about that, too.”
Then they took their places, and Mr. Broderick found his orchestra seat next to his wife, Sarah Jessica Parker. Forty-five minutes later, he was summoned to the stage to wild cheers. He blinked into the lights, boyish and bashful, before taking his seat in between the comedians, who crowded in around him.
They teased him about his Greenwich Village upbringing (“Did you like crawl around smoking roaches?”) and his “Glory” mustache. Mr. Kroll turned the revelation that Mr. Broderick had gone to the Walden School into an uproarious bit about Walden Pond and public urination.
Ms. Parker could be heard chortling throughout, but Mr. Broderick seemed to find it a bit surreal. “I was watching the play, and now I’m in the play,” he said onstage.
When the sandwich arrived, in a riot of glitter, hymn and angel wings, both men pounced on Mr. Broderick’s religious inheritance. “For the Christian side of you, look how it descended,” Mr. Mulaney said.
“And for the Jewish side, look what it is!” Mr. Kroll enthused.
Mr. Broderick toyed with a few of the toothpicks, but declined to take a bite, which was probably lucky for Mr. Mulaney. Back in his dressing room, after the show, he congratulated himself on not feeding the meter, even when faced with so much tuna. It had been a near thing. “We’ve done this for 10 years,” he said. “But today, I thought, this prank is not funny.”