Have you heard the one about the lifelong stutterer who wants to be a stand-up comic? That sounds like the start of an utterly tasteless joke, but 19-year-old Donnie Sengstack is not only a true story, he's the reason I'm now (relatively) up to speed on stuttering.

Let me explain. The National Stuttering Association, the largest support organization for the 68 million people on the planet who live with this speech problem, is here in Washington this week for its annual conference. And as often happens, I was contacted by the group's publicity folks to see if I wanted to cover the meeting.

If you're like me, you know maybe two things about stuttering: Colin Firth did one hell of a job playing King George VI in "The King's Speech" and stutterers are the victims of some kind of childhood emotional problem.

It turns out that while the former is undeniably true (Firth won the 2011 Oscar for best actor), the latter is totally false. We'll get to that in a minute.

The folks at the stuttering organization (their acronym, NSA, has an entirely different meaning here in D.C.) suggested I catch Sengstack's stand-up routine. But the timing didn't work out, so I invited him down to the Post to do a few minutes in our studio. You can see the results in the video posted above.

Sengstack can't remember a time when he didn't stutter and for almost as long, he has written jokes and wanted to perform them. About the time he graduated high school, he began to seek out "open mic" nights in Washington, Baltimore and New York. Instead of being embarrassed about stuttering, he realized he had an advantage over other comics by bringing up his stutter at the beginning of his routine and riffing about it throughout.

Because of the stutter, he notes, "I can turn a one-liner into an HBO special." And, he says, "the ladies tell me I put the stud in stutter." He goes on about his stuttering efforts to make the Siri feature on his smart phone understand him. It's pretty novel, and funny, stuff. Sengstack was a finalist at the New Comedian of the Year competition at Magooby's Joke House in Timonium, Md., and has been paid to do stand-up even though he just finished his freshman year at the University of Maryland (where he studies communications, of course).

Sengstack says he was teased as a child, but not for very long, because "I'd say something funny" and that would be the end of it. Now he plans to either perform or write comedy as a career, but at the same time, he feels an obligation to other people who stutter.

"I want to convince kids not to view it as a disability," he says. "I just view it as something I have."

So what causes stuttering? Well no one really knows, but research has shown that this complex disorder isn't the result of emotional problems, overbearing parents or hyper-anxious kids, according to Nina Reeves, a speech language pathologist in McKinney, Tex., who serves on the NSA's advisory board. (One stutterer Reeves knows likes to say, "I don't stutter because I'm nervous, I'm nervous because I'm stuttering.")

There does appear to be a genetic link; stuttering runs in families. Beyond that, Reeves says, the cause is some mixture of temperament, environment, child development and brain chemistry. Males are more commonly affected than females. Some people are very good at coping with it and mastering it--Vice President Biden and actor James Earl Jones are two famous people who stutter, though you probably wouldn't know it if  you listen to them. Stutters take different forms and can be more or less severe, and, yes, they do sometimes get worse when the stutterer is under pressure. (Here's a good Q and A on stuttering basics.)

"This is brain development," Reeves says. "The biggest problem with stuttering is people try to fit it into a box…it’s just too complex to put in a box and put a bow on it."

Some children will go through a stuttering period between the ages of 2 1/2 and 5, but most come through it fine. For those who don't and continue to stutter throughout their lives, there is no cure. The most common approach is to manage it, to prevent it from interfering with the stutterer's life.

The goal is "effective communication," Reeves says, to be able to "say what you want, when you want, to whom you want, whether you stutter or not."