Adam Pally ate some tuna. Chelsea Handler swallowed a mouthful. Chris Pratt attacked the sandwich and took three huge bites before the meal ultimately got the better of him. “It was still too much tuna,” the comedian Nick Kroll said.

“Too Much Tuna” is the title of a prank skit that Mr. Kroll and his friend, the comedian John Mulaney, invented a decade ago. It has become a highlight of “Oh, Hello on Broadway,” a comedy that Ben Brantley, writing in The New York Times, called “stupendously entertaining.” The show stars Mr. Kroll, 38, as Gil Faizon, an unsuccessful actor and “the type of man you would catch at a party going through the coats,” and Mr. Mulaney, 34, as George St. Geegland, an unheralded novelist and “the kind of guy who flosses on the bus.”

While in character as Upper West Side geezers, they interview a different celebrity guest at each performance, typically a fellow comedian, a theater legend or a seminal New Yorker, like Pat Kiernan of NY1.

The men, who also wrote the show, don’t do much prep before each interview. “We read people’s Wikipedia page,” Mr. Kroll said. “Find out that their mother sang light opera,” Mr. Mulaney said. But mostly they prefer to see where the conversation takes them. At the end, they confront the guest with a three-pound tuna sandwich, a snack so gigantic it might pose a mercury poisoning risk to anyone nearby.