Paul Mecurio was working on Wall Street, helping put together billion-dollar deals. Then he sold a joke to Jay Leno for $50, and his life changed. 

An Emmy and Peabody award winner for his writing on “The Daily Show With Jon Stewart,” Mecurio will moderate Chabad of St. Louis’ Jewish Law & Ethics Symposium on Thursday, June 12, at the Sheraton Clayton Plaza. 

He brings a wealth of experience to the role: a law degree from Georgetown University and experience in the rarified field of mergers and acquisitions; standup comedy; movies and TV sitcoms; “Daily Show” and “Colbert Report” political satire; talking-head punditry on wildly different outlets including Fox News and ESPN sports; and as a podcast host pressing people such as Paul McCartney and wrestler Stone Cold Steve Austin on how they do what they do. 

So Mecurio should be at ease at the symposium, which will feature a panel of retired federal District Court Judge Stephen N. Limbaugh; Rabbi Shlomo Yaffe, dean of the Institute of American and Talmudic Law; and Cathy Steele, a St. Louis lawyer and president of the  Jewish Children’s Home and the Jewish Family and Children’s Service. They will be  discussing legal ethics, religious and public-policy flashpoints, and recent First Amendment issues.  

The Jewish Light reached Mecurio by phone at his New York office and asked him to finish this sentence: A rabbi, a judge, a lawyer and a comedy writer walk into a bar …

“And,” he quickly said, laughing, “the bartender goes, ‘I know the comedy writer’s not paying, because he’s making less money than all of you combined.’ (The symposium) should be a fun night, I’m looking forward to it.” 

Mecurio gave up the high-paycheck security of Wall Street for, as he says, “telling jokes to drunks” in sketchy bars, for a reason. 

“Let’s be honest,” he says. “Italians and people of the Jewish faith are very similar. It’s about family and food. We’re kind of loud, a lot of yelling. So I decided — and Jewish people would appreciate this — I just wanted to see how quickly I could give my mother a heart attack.”

But seriously, folks, Mecurio’s second act grew out of a secret life that began with a cache of jokes he wrote as a hobby and kept in a password-protected file on his work computer. He didn’t know what he was going to do with them until, one night, then-“Tonight Show” host Jay Leno appeared at a private function put on by his firm. 

“I went up to him afterward with all these jokes and I go, ‘Look, I don’t know if you want some jokes, I don’t know what to do with them, you can have them,’ ” Mecurio says, breaking into a Leno impression. 

“He called me the next day and said, ‘This stuff is clean, it’s funny, and I always need new, fresh material for the “Tonight Show” monologue, so start sending me jokes, and if I like something, I’ll use it, I’ll pay you 50 bucks for it.’ ” 

The first joke Leno used on the air was about the fixer-upper TV show “This Old House” and how “it didn’t reflect reality, because the contractor was always really polite, neat, on time, under budget, and in real life he’s four months over time, $50,000 over budget, drunk … and mocks you.”

“For a middle-class kid who lived in New York, got hired by a big-time firm as a lawyer, you’d think that’s pretty heady stuff, because I was doing these deals that were on the cover of the Wall Street Journal, and yet this little $50 joke had way more power over me,” Mecurio says. 

At Leno’s urging, Mecurio began field-testing jokes at bars and clubs with open mic nights, using his dinner hour to perform at a dive in New York’s Bowery called Downtown Beirut 2. (“It’s like they were franchising these hellholes, or Israeli fighters took out No. 1.”) 

For a couple of years, Mecurio was able to keep his two lives separate. Then one night his one-hour club gig turned into four hours, causing him to miss a big deal — a deal that cratered. When a more senior lawyer pointed the finger of blame at Mecurio, the soon-to-be-full-time comic reflexively fired off a rude comeback honed against hecklers at Downtown Beirut 2: “Yeah, well I could have been your father, but the dog beat me over the fence.”

After his comedy career took off and his award-winning work for the “Daily Show” gave him “street cred,” he began getting invitations to appear on news and talk-show panels:  Fox News with Sean Hannity talking about the Egyptian uprising and racial profiling; CNN discussing “Oddball Boss Requests”; ESPN’s “Sportsnation” on a New York Jets quarterback controversy; Fox Business’ “The Independents” on Obamacare; and with Katie Couric talking about beleaguered pop idol Justin Bieber (“He lip-synced his testimony”).

“I usually get the topics ahead of time, and I try to prepare a little bit,” Mecurio says. “I try to have a strong point of view and be funny, as opposed to just coming in with random jokes from my act. Like we’re talking about Benghazi and I’m going, ‘Wow, pie really fills you up, huh?’ It doesn’t really match. 

“And it’s fine, and it’s fun. But it is disconcerting sometimes because I feel my job is to be like an X-factor, to call everybody on their BS. Because we live in a culture where both sides, the Republicans and the Democrats, are so locked into their talking points.”

Will Mecurio bring those preparation habits to Chabad’s symposium? Has he been studying the 63 volumes of Talmudic law as homework?  

“Actually, the day after tomorrow, I convert to Judaism,” he laughs. “I am getting fitted for a yarmulke. I think I’m good to go. 

“No, I’m gonna moderate this conversation, and I’m really looking forward to it. We’re going to talk a little bit about me, that I was a lawyer. They thought it would be fun for people to hear that I made that transition. And I’m talking with the folks who are putting it together … (about) a whole host of subjects that I’m gonna study up on. 

“But I will be doing it in Hebrew,” Mecurio laughs again. “I’m coming, man, I’m coming.”