This was something that Fielder would never utter, of course, in his on-screen guise. Although he once seriously considered a career in business, that world and its preoccupations have long struck him as ripe for laughs. A moral streak, however submerged and slippery, inflects his show, which serves as both a loving tribute to scrappy entrepreneurial gumption and an offbeat assault on the way such gumption can curdle into predatory greed. With “Nathan for You,” Fielder said, the joke is that he inhabits that unscrupulous mentality to a near-sociopathic extreme: “It’s funny to lean into that idea of: ‘How can we push product? How can we sell stuff?’ without thinking any more broadly about what you’re doing and how it benefits the world.”

On Fielder’s desk there was an odd-looking toy, composed of a fuzzy halo of webbed coronets sprouting from a central hub. “It’s basically a worse ball,” Fielder said. “It doesn’t go as far or bounce as high, and it’s hard to catch.” The toy was called a Doinkit, and for a coming episode of “Nathan for You,” Fielder had offered his services to its manufacturer, Marky Sparky Toys, experimenting with a marketing campaign that preyed crassly on the insecurities of the target demographic: young children. Owning a Doinkit, Fielder’s copy asserted, is the only way to prove you’re not a baby. This bullying message would unfold in various forms, from packaging that Fielder designed (a Doinkitless child of about 6 slumps dejectedly in diapers while others mock him), to a hectoring television commercial, to a mall Santa instructed to give kids the hard sell: “You aren’t a baby, are you?” The subtext was that advertising is designed to make people of all ages feel inadequate and incomplete; Fielder, whose wife is a children’s librarian, wanted to know what it would look like if he applied that logic coldly and rigorously to first graders. (Fielder likes incorporating children into the show, framing his character’s perversity against their innocence.)

Around 10 a.m., Michael Koman, co-creator of “Nathan for You,” arrived at the office. Koman’s résumé includes writing positions on “Late Night With Conan O’Brien” and “The Colbert Report.” He and Fielder walked to a room down the hall, where an editor named Eric Notarnicola was stitching together a provisional cut of the Doinkit segment. “It’s basically selling children an identity, the same way you sell adults a Lexus,” Koman said.

Many people suspect that reality television is scripted, and with “Nathan for You,” this is, in a sense, the case. Fielder and his writers compose detailed outlines for each episode, trying their best to predict “what a reasonable person might say in a situation,” Fielder said, and to steer events in propitious directions — nudging customers from the gas station, for example, to the mountaintop. This doesn’t mean that the show’s marks are acting, however, or in on the joke: Fielder’s producers approach prospective businesses without letting on that “Nathan for You” is a comedy show, and Fielder never breaks character at a shoot. He avoids going big with his performance, which helps him to pivot nimbly from laugh-getter to straight man, depending on how his interlocutors react to whatever crazy idea he’s selling. In one episode, Fielder proposes that a delicatessen manager named Gloria allow noncustomers to use her restrooms and that she advertise this policy around the neighborhood, arguing that the increased foot traffic will be worth it. Fielder presents his pitch with winning enthusiasm, and with an air of soft-spoken naïveté that helps smooth away any underlying meanness in the moment: “You guys could become the neighborhood toilet,” he tells her. Gloria glances around as if for help, but Fielder simply lets her discomfort hang in the air. Finally, politeness gets the better of Gloria’s judgment, and she says, “Yeah, I guess that’s a good idea.”

In filming the show, Fielder says, chance ultimately rules: “We don’t even reference the script after a certain point. An entire day of shooting will ride on stuff happening the way we hope. It’s crazy to do a production like that, but the uncertainty makes the show feel more authentic and spontaneous.” Koman agreed: “It’s setups and luck.” The way Fielder manages this unpredictability is to shoot an excess of footage: He may need only one kid sitting on Santa’s lap with a Doinkit, but he’ll film three to ensure that he’s covered. “This show shoots more footage than anything I’ve worked on,” Notarnicola said, sitting at his editing bay. Fielder said, “Only a few things keep making you laugh the 10th, 12th, 15th time you watch them, though, so it gets easier to cut as you go.”

Notarnicola dialed up footage from a focus group composed of Fielder and three young children. “This is me testing out whether the pitch will work and get kids to want the toy,” Fielder explained. On-screen, in a tie and ill-fitting button-down shirt, Fielder held a Doinkit and quizzed his prepubescent panel. “When I show this to you, what do you think? Do you want it?”