Korbyl's 14 classmates applaud politely.

"Good job," says instructor Darren LaCroix.

It is the first of two days of Humor Boot Camp, a biannual seminar designed to help executives inject humor into their speeches and business interactions. This is its first Las Vegas sojourn.

"Humor is one of the most underutilized tools in the business world," LaCroix said earlier. "Humor gets people to listen. It builds rapport to make the sale, and people want to do business with people they have fun with."

Las Vegas stand-up comedian Vinnie Favorito, LaCroix's co-instructor, interrupts the polite applause from the side of the theater in which he performs every evening.

"Did you really buy that?" he asks the class, "or were you being nice?"

LaCroix's smile narrows.

"I accepted it," he tells Favorito.

Although LaCroix founded Humor Boot Camp in 1998, it's Favorito who is the real humor expert here. Fifteen years ago, he taught LaCroix -- then a failed Subway restaurant owner -- how to speak in public during one of his comedy seminars in their native Boston.

"You accepted it," Favorito continues, "but you didn't buy it."

Korbyl is asked to repeat himself.

"I'm not here to kiss your ass," Favorito says later. "I'm hear to tell you the truth. I wouldn't want to pay to have some guy lie to me."

LaCroix toured his motivational seminar across the country for a decade, but always wanted to include Favorito. So, in October, he committed to making Las Vegas its -- and his -- permanent new home.

"I wanted to do it with my mentor," LaCroix said. "When I first came to him, it was pathetic. I would shake so badly onstage, he would hand me a cup of coffee just to watch it shake."

Humor Boot Camp costs $895 per person.

"It was worth it," says Gretchen Givone, 41, a Las Vegas aesthetician who signed up to improve her ability to convince skeptics about Endermologie, a new kind of body-contouring service she provides.

"They taught me how to inject a little bit of humor into a topic that is more or less serious," she says.

Topics also included the difference between positive and negative humor, how to make scripted material feel improvised and the comedic thought process.

On Friday -- 24 hours and about as many exercises after his "yeah, right" debacle -- Korbyl returns to the stage a different businessman. Most of his stage fright is gone, replaced by an emotional commitment to his material.

"It's a pleasure to be speaking for the annual stockholders meeting," he says, waiting a confident beat before delivering his punch line. (In addition to three minutes to write, Favorito has given the class a premise: to deliver the opening line to a speech for a large doughnut company.)

"Or let's face it," Korbyl says, "the Policeman's Benevolent Association."

The crowd applauds for real this time.

Contact reporter Corey Levitan at clevitan@reviewjournal.com or (702) 383-0456.