With partner Teller on 'Penn & Teller.' Showtime

For someone who has spent a career crusading against fakery and false idolatry, Penn Jillette sure is doing a lot of reality TV these days. Last Friday, the producers of "All-Star Celebrity Apprentice" allowed him one day off from a relentless taping schedule for episodes to air in March, and he breathed the air of midtown Manhattan like a paroled prisoner. Even with a new book out, "Every Day Is an Atheist Holiday!," he was consumed with the TV show.

"It's a great day for me," he said. "You are not on the 'Apprentice' show, so you can't believe how happy I am to see you. You've never interviewed anyone who's happier to talk to you."

The magician-comedian-writer Penn Jillette has made a career out of misdirection--both performing magic and demystifying it, appearing on "The Celebrity Apprentice" and railing against fakery. Don Steinberg has details on Lunch Break. Photo: Getty Images.

"Celebrity Apprentice," in case you've missed it, is the "celebrity" version of a game show that Donald Trump has hosted since 2004, in which contestants perform quasi-business tasks and hope to remain the last one standing after Mr. Trump fires everybody else.

"It's a pretend show about a pretend game, about pretend business, where you pretend to get fired," Mr. Jillette explains. In his new book he provides an even more inspired synopsis of the show, on which he was a cast member in a previous season: "venal people clawing at stupid, soulless s— in front of the modern-day Scrooge McDuck in order to stay famous."

Mr. Jillette juggling in the 1970s. Penn Jillette

Mr. Jillette with Marilu Henner and Dee Snider on 'All-Star Celebrity Apprentice.' NBC

From the Showtime series 'Penn & Teller.' Showtime

The cover for Mr. Jillette's new book, 'Every Day Is an Atheist Holiday!'

Mr. Jillette is hard to figure. At 57, he has spent much of his career—most of it with his nonspeaking performing partner Teller in their stunt-filled Las Vegas comedy-magic act—bashing shams and scams. Penn & Teller regularly expose fraud and hype within the magic-act business, and for eight years they did a TV show called "Bulls—," where they challenged a litany of sacred cows and popular beliefs (ESP, organic foods, the animal rights movement). Participating in a patently bogus enterprise like reality TV would seem, in the parlance of modern celebrity, to dilute his personal brand.

His image is mixed up enough already. Penn and Teller are magicians and antimagicians. They do a child-friendly stage show, but Mr. Jillette produced a documentary, "The Aristocrats," about one of the filthiest jokes ever uttered. Mr. Jillette doesn't drink alcohol or use drugs but as a Libertarian says he wouldn't oppose legalizing, say, heroin. He's a devoted family man who admits in his new book that his rich portfolio of lewd acts includes having nude-wrestled a dwarf.

Bottom line, Penn Jillette is a professional misdirectionist. If you figure out what he's going to do next, the jig is up. Unpredictability is his brand, and for him it's a license to pursue whatever he thinks might be a thrill, even reality TV.

"If it were 1968, I'd wanna be on 'The Ed Sullivan Show.' I'd wanna be the magic act after the Beatles," he explains. "For better or worse, in the 21st century, reality shows are the variety show. And which is a better story: 'I watched Gary Busey go apes— on "Celebrity Apprentice," ' or 'I stood next to Gary Busey when he was going apes— on "Celebrity Apprentice?" ' "

"Like any carny, he's all about getting people into the tent," says Lawrence O'Donnell, the MSNBC commentator whom Mr. Jillette calls his best friend. "Nothing gets them into the tent like reality shows."

His books are where we get the unfiltered Penn. "Every Day Is an Atheist Holiday!" nominally is an atheist's take on American holidays. Who wouldn't want advice about April Fools' Day from America's trickster laureate? But in Mr. Jillette's writing, as in life, you never know where he's headed.

The best parts are random, profane but delicious insider stories that few others can deliver. The April Fools' chapter rambles from Penn & Teller's cameo TV appearances to an intricate trading of pranks between Mr. Jillette and Arno Penzias, a Nobel Prize-winning Bell Labs physicist. Mr. Jillette helps lab staffers stage an elaborate fake-technology demonstration to fool Mr. Penzias—in keeping with Mr. Jillette's theory that pranks should honor their targets, not be cruel. Afterward Mr. Jillette coaches Mr. Penzias on how to open his presentation at the prestigious TED conference in 1995 with a dirty joke. Neither of them really expects Mr. Penzias to tell the joke during the talk, but when he takes the stage, the scientist is goaded into it by an audience member— Jonas Salk —and it brings down the house.

Write to Don Steinberg at don.steinberg@wsj.com