He’s a Long Way From the Water Cooler : Television: Carlos Mencia, hosting ‘Loco Slam’ this month, turned to comedy after being encouraged by his co-workers at an insurance company.

For a guy with a stand-up comedy career that’s currently zipping along like a bullet train, Carlos Mencia has a shocking admission to make.

“I was never a funny guy,” says the 25-year-old native of East Los Angeles. “I was never the guy cracking jokes at school. I was the kid in the back of the classroom who shut up and did his work. Half the students didn’t know who I was, and the other half hated me for ruining the grading curve.”

Anyone who has seen this graduate of Garfield High stalking a comedy club stage might find it hard to believe that the energetic, irreverent performer was ever the quiet type. The young comic takes on his audiences with a mix of streetwise bravado and exuberant playfulness, often working himself into a voluble frenzy. Alternately crude and crafty, Mencia holds nothing back, whether he’s discussing the lighter side of condoms or the uglier aspects of racism.

Now, Mencia’s mix of insight and outrage can be heard nationwide. This month he has been hosting HBO’s “Loco Slam,” a late-night, “Def Comedy Jam”-styled stand-up show geared toward a Latino audience. He’ll also get his first comedy special on the July 7 “HBO Comedy Half-Hour.” And he has completed a sitcom pilot, which is currently being shopped around.

“It’s a rush to have good things happening for me,” Mencia says. “But I’ve always had a very strong work ethic. I’m an aggressive person. For the last four years I’ve worked an average of 10 times a week in the clubs, and sometimes I’ve done six sets all over town in one night. As soon as I saw I could get people to laugh, I wanted to be as funny as humanly possible.”

Mencia’s first step toward the world of stand-up was taken in the unlikely offices of Farmers Insurance, where he worked full time while carrying a full course load in electrical engineering at Cal State Los Angeles. Mencia started attracting a crowd around the water cooler as he re-interpreted the jokes he’d picked up from comics on “The Tonight Show.” Rather than muzzle him, his superiors encouraged him to make a career switch.

“This old guy who I’d never seen smile called me into the office one day. I was shocked when he said I should consider doing stand-up for a living. I dismissed the idea at first, but I told one of my cousins about it, and he finally talked me into giving it a try. I signed up for an open mike slot at the Laugh Factory. We got three minutes, and I ran out of material in 2 1/2. But I got some laughs. I knew I didn’t want to be an electrical engineer anymore.”

Mencia quickly settled in at the Comedy Store, where, aside from developing his stage skills, he also parked cars and worked the door. “That was my training ground. I watched every comic I could to study what worked and what didn’t. I recorded myself every time I was on stage and listened to it on the way home. I was methodical. And I started to get confident. Then, when I saw Paul Mooney, who could talk about racial troubles and be hilarious at the same time, I realized there was more to this comedy thing than making people laugh. I realized you could teach people through laughter.”

What Mencia seeks to teach is tolerance.

“It becomes a ‘we’ thing on stage. Even if I’m saying things in an angry way, it speaks to the anger in everybody. You don’t have to be Latin to understand the fact that having no Mexicans in Taco Bell commercials is wrong. We can all recognize stupidity together. In my act, I talk about this cleaners’ sign I’ve seen--’Open 7 days a week, including Sunday.’ The sign reads that way because somebody kept asking, ‘Seven days a week? What about Sunday?’ A crowd of any color can understand what’s stupid and funny about that.”

That’s not to say that Mencia hasn’t been challenged by audience members. At one Comedy Store show, a patron threatened to assault him if the comic didn’t stop poking fun at white people.

“I said, ‘Look, you guys made a movie called “Green Card” without any Mexicans in it. You made a movie called “Alien” without any Mexicans in it. The only time Mexicans get into movies about the future is when Ricardo Montalban steals a spaceship. If we made a movie called “Gold Card” and didn’t put any white people in it, you’d be pissed too.’ ”

From there, Mencia launched into a comic rant that broke the crowd up completely, and eventually even the heckler was won over. “After the show he asked me for my number, and now he comes to see me all the time. Those are the shows that are important. If you can get a guy to go from wanting to kick your butt, to wanting to see your act again, you’re doing all right.”

* “Loco Slam” airs Friday at midnight on HBO. Mencia’s appearance on “HBO Comedy Half-Hour” airs July 7 at 11 p.m.