An out-of-work Lehman Brothers broker, a laid-off Ford autoworker, and a broke A.I.G. executive walk into a bar…and they probably don't want to hear a joke.

There's not much to laugh about in these tough economic times, with companies failing and jobs vanishing. But humor consultants, citing decades of research, say levity is exactly what's necessary. Encouraging employees to have fun can boost morale, foster creativity, reduce absenteeism, and increase profits.

"Companies where humor is part of the culture have a competitive advantage," says John Morreall, a humor consultant in Williamsburg, Virginia, whose clients include Corning, I.B.M., and Cargill.

A classic example is Southwest Airlines, whose zany founder Herb Kelleher is known for wearing Easter-bunny suits and jumping out of overhead bins. Flight attendants often break into song, and the corporate headquarters has a volleyball court.

"They've done well, even when other airlines are struggling," says Morreall, who is also a religion professor at the College of William and Mary.

But is it possible to teach lightheartedness, especially when things seem as dire as they seem today? Can companies mandate fun? Humor is subjective, after all; what cracks up Ed in engineering won't necessarily amuse Mary in marketing.

"It's not about teaching people how to tell jokes or be wacky," says Edward Dunkelblau, a humor consultant in Northbrook, Illinois, whose clients include United Airlines, Allstate, and Accenture. "It's about teaching them to be playful and find enjoyment in their jobs—no matter how difficult the times may be."

Dunkelblau, a clinical psychologist, says he tells "humor impaired" executives who seek his counsel that something as simple as keeping a Slinky on their desk can make them more approachable and send a signal to employees that it's okay to have fun at work. "They are amazed at how many people pick these things up and play with them," he says.

He also encourages overly serious managers to keep humor journals of things they find amusing and to share those things with others: "The idea is that they don't have to be funny, but they have to recognize what is funny."

Humor consultants say corporate clients typically call on them during stressful times—following layoffs, amid a buyout, or perhaps after the introduction of a new computer system. Fees range from $500 for a speech to $50,000 for several months of assessment and intervention.

Playwood Systems, a family-owned playground-equipment maker in Lewisburg, Pennsylvania, hired a humor consultant last year simply because it wanted its culture to reflect its product. "You could walk around the building and it was so serious; you'd have no idea what we did," says Kevin Cook, Playwood's director of sales and marketing.

Over six months, Playwood's management worked with ChartHouse Learning of Burnsville, Minnesota, to encourage a more open and fun workplace. Cook says the office was redecorated using lively colors; employees were encouraged to use bulletin boards in public areas to post pictures of themselves doing what they loved when they weren't working.

Department heads also dreamed up events like "Jimmy Buffett days," playing the singer's music while serving key lime pie. If a department reaches a sales goal, everyone makes an afternoon run to a nearby ice-cream parlor. "The idea is that we can be serious about work but not so serious about ourselves," says Cook.

Executives, however, should be serious about humor, consultants say. Some say they won't work for a company if management doesn't agree to lead by example.

"Humor flows downhill like everything else," said Bob Mankoff, cartoon editor for the New Yorker (which, like Condé Nast Portfolio, is published by Condé Nast). An experimental psychologist by training, Mankoff conducts humor seminars at Fortune 500 companies as a sideline.

Mankoff said his approach is to ask a company's executives about what they see as problem areas—such as communication or micromanagement—before he addresses the troops. In his presentation, Mankoff draws cartoons on the subject and asks employees to write captions. (We've gathered some of Mankoff's cartoons are in a slideshow.)

"Frustration and anger create tunnel vision, but laughter is a broadening emotion that opens up creative and problem-solving channels," Mankoff says.

Patricia Clerico-Parham of Cisco Systems says Mankoff's presentation there last year helped "defuse tension in a competitive environment where there's not much downtime." His talk was "an important reminder that it's okay to have fun, and brainstorming is not about blaming," she adds.

Not all humor consultants are effective, of course. Some are frustrated comedians whose shtick would get them booed out of some clubs, according to companies that have hired them.

Take the humor consultant who wore a red rubber clown nose while speaking to a regional gathering of State Farm employees. Spokeswoman Carolyn Fujioka says he was "pretty lame and he provided no revelations."

A consultant who served up platitudes like "humor is a life-giving liquid" and "humor occurs at the speed of trust" to management trainees at McDonald's also was not well received. The company official who booked the guy angrily hung up on this reporter when asked about the experience.

Humor consultants who help employees discover how to have fun get better reviews than those who speechify or do stand-up routines.

Ann Fry, a psychotherapist turned humor consultant in New York City, said she uses role-playing exercises to help employees come up with humorous ways to deal with difficult situations. She has advised people at Shell Oil and Genzyme, among other companies.

One client, Tim Warneke, senior director of King Pharmaceuticals in Cary, North Carolina, says these sessions not only help employees learn how to "bring fun to work" but also coaches them on what is appropriate humor. "She gives feedback on what is and isn't going to fly," he says.

Of course, not everyone has the same sense of humor. Geography, gender, and status in the company may influence what people consider funny. Generally, consultants say that teasing or belittling humor is destructive, while humor that captures the absurdity or irony of situations promotes camaraderie.

"Humor will always exist as a coping mechanism," Mankoff says. "The trick for companies is to harness it so it's constructive, not subversive."