LOS ANGELES — Tom Irwin has done four tours in Iraq, where his job is to kill, but not to bomb.

Irwin is a stand-up comic who has been entertaining the troops in dangerous places such as Mosul and Fallujah. His mission, as he sees it, is two-pronged: to keep America's soldiers laughing and to make folks back home aware that what the troops are doing is deadly serious business.

The 39-year-old entertainer draws his humor from what he finds in Iraq as well as from his days in the Army two decades ago at Fort Leonard Wood, Mo.

"When I do shows for Marines, I always tell them that I was in the Army because they always boo me," he said. "Telling a group of Marines you were in the Army is like telling them you have a flair for interior design."

He tells the troops in Iraq that their war's hipness quotient is low. Vietnam War movies, he explains, always contain a scene set to psychedelic music that shows soldiers "wearing bandannas, smoking drugs, listening to Hendrix, all trippy and stuff."

"What the hell is your movie going to be about?" he says. "They're going to cut to the musical montage and they'll be two guys playing Ping-Pong to a Hilary Duff song."

Much of the rest of his act is filled with dark (and unprintable) humor about military life, including observations about latrine duty, barracks sexual escapades, military rivalries and, of course, the food.

He has put together a one-man show on DVD, "25 Days in Iraq," that chronicles his first visit, nearly three years ago.

"My goal is just to make sure that those people don't get forgotten," he said, safely ensconced for the moment on the patio of his favorite coffee shop on a fashionably funky Los Angeles street.

Irwin and his fellow journeymen comedians get their bookings through Michigan-based Comics on Duty, which has 75 or so comics.

"It's about the mission," said Comics on Duty founder Rich Davis. "If a comic calls me and says, 'How much does it pay?', I don't call them back."

Comedian Derek Richards recalled arriving there in 2004 to discover soldiers dumbfounded that comics were in their midst. The area was so dangerous, they told the comics, that even the reporters covering the war stayed away.

"I went, 'Oh, sweet Jesus, what did we get ourselves into?' " said Richards, who lives in West Palm Beach, Fla.

At a base in Mosul, a show that included Irwin and Richards was delayed when the area came under mortar fire. After the explosions stopped, the performance continued.

"They said, 'The good news is that it's all clear ... and the better news is that the mortar rounds all landed right where you guys were standing about an hour ago,' " Irwin recalled. (The show was at a mess hall that a suicide bomber blew up later that year, killing 22 people.)

Irwin asks his audience to remember that, no matter what people think of the war, the troops are coming home from it all the time.

"And when they do come home ..." he adds, his voice catching, "please, be nice to them."