“All my actor friends are really mad at me,” confessed Jay Reiss from the comfort of his dressing room at the Circle in the Square Theatre.

They should be. Though playwright is his stated profession, Mr. Reiss, 37, is currently pulling down an Equity salary and a majority of the laughs playing Vice Principal Douglas Panch in the Broadway production of the hit William Finn-Rachel Sheinkin musical, “The 25th Annual Putnam County Spelling Bee.”

Panch is the fictional bee’s word pronouncer. In this capacity, he mercilessly doles out such brain busters as the ocular malady “strabismus,” followed by hilariously disconcerting word-usage sentences such as, “In the schoolyard, Billy protested that he wasn’t cockeyed. ‘I suffer from strabismus,’ he said, whereupon the bullies beat him harder.”

That particular line brings down the house every night. Many others are equally effective. It’s the sort of part approval-hungry actors yearn for. So how did a dramatist with almost no onstage experience nab such a plum assignment? It’s an old story: He slept with the director.

“My girlfriend, Rebecca Feldman, she had the idea for the show,” Mr. Reiss said. Ms. Feldman shaped the 2002 off-off-Broadway show “CR-E-P-U-S-C-U-L-E,” which was the precursor of “Bee,” and also starred Mr. Reiss, as well as many other cast members who are still with the project. “We were lying in bed. She said, ‘Do you want to be in it?’ I said, ‘Sure, it will be fun.'”

And it has been. One thing the novice actor particularly likes is that much of his part is written on index cards. “Reading from the cards is a big thing,” Mr. Reiss said with a slow, droll nod of his head. “That’s not to be undervalued, that whole concept.” An even better perk is that, beginning with the downtown production, all the words and their sample sentences on those cards have been selected and crafted by Mr. Reiss himself. That includes “capybara,” the large South American rodent (as in, “Don’t look now, Pedro, but I think that tailless four-and-a-half foot rodent swimming next to you may be a capybara”), and “phylactery,” the leather boxes worn by religious Jews during morning prayer (“Billy, put down that phylactery – we’re Episcopalians”).

Few observers were aware of his textual contributions during the sold-out run of “Spelling Bee” at Second Stage earlier this year. Critics quoted his lines without realizing that their author and the heavy lidded, auburn-haired performer with the plaid pants and the dead-on deadpan delivery were one and the same person. That frustration has been rectified by a new credit, “Additional material by Jay Reiss.” It sits right below the “Conceived by Rebecca Feldman” credit on the title page, which seems to please the latter’s boyfriend to no end. (James Lapine has taken over as director for the Broadway mounting.)

Because the eccentric, partly improvisational musical recruits volunteer bee participants from the audience every night, Mr. Reiss has ample opportunity to introduce new words into the show. He finds them just the way anyone might: by flipping through the dictionary. He does, however, occasionally employ a more difficult method. “I’ll say something in my regular life, and I’ll think, ‘Hey, I can actually craft that into a sentence.’ Then I’ll have to find a word that means that thing I was saying. I literally spent hours once trying to find a word for a fish with teeth that wasn’t ‘piranha.'”

One imagines that new material might come as a shock to the cast, especially when the lines are as funny as Mr. Reiss’s. Do fresh lines sometimes result is an unscripted smile and snicker? Mr. Reiss, who has a sneaky sense of humor, allows himself a thin, Machiavellian smile. “It happens,” he said.

Mr. Reiss grew up in Plainview, Long Island. His mother was a manager at Off-Track Betting, and his father was a health inspector and scientist who preferred to get his action trackside. “He liked to play the ponies,” Mr. Reiss said. “He’d take me all the time. Because he’s a scientist, he has these complicated mathematical systems for playing the horses. And it’s all $2 bets. He taught me his crap system once. He said, ‘You can’t lose. You won’t really win too much, but you can’t lose.’ It was all about how to hold on and increment your bets while you wait for the streak to come.” Dad now lives in Las Vegas.

Mr. Reiss’s degree in cinema at SUNY Binghamton led, oddly enough, to writing sketch comedy for an improv group called After Hours. Sketches grew into 10-minute plays, which eventually mushroomed into full-lengths. Mr. Reiss’s most high-profile productions – whimsically titled pieces such as “Meanwhile, on the Other Side of Mount Vesuvius,” and “Hooray for Iceboy” – have been presented by the Adobe Theatre Company. It was Adobe, actually, that gave him his first big acting break, in a two night run of a little show called “Bobby Lei’s Honolulu Hawaii.” “I’m very proud of my work as a cop in that,” Mr. Reiss said.

That Mr. Reiss is still getting the feel of the actor’s life is evident. For instance, he only wanted to do the Broadway run for three months tops. His producers shook their mighty heads and told the rookie it was one year or nothing. Also, he doesn’t seem overly thrilled about having to join Actors’ Equity. “I’m a member of the Writers Guild and the Dramatists Guild. That’s enough dues. It’s expensive, that Equity.”

Another unwelcome surprise was the day-to-day sameness that’s part and parcel of the long run. “There were times at Second Stage,” he said, “where I’d say to the other actors, ‘So this is it? You just do the same thing for months?’ And they’d say, ‘Yep, pretty much: plateau.’ I experience times where I say, ‘I can’t do it. Another performance. I can’t.’ Then you come through that and you think, ‘This is the greatest job in the world. I work two hours a night.'”

Two hours a night. Lots of laughs. A writing credit. Nice work if you can get it. And then there’s the icing. “The best part of acting is free haircuts,” said Mr. Reiss, who grew long, 1970s-style sideburns to get in touch with his inner vice principal. “Every three weeks. My hair grows fast. Love those free haircuts.”