When Steve Mizerak Jr. picks up his pool cue in that popular TV ad for Miller's Lite beer, he looks like the kind of low-down hustler you want your kids to stay miles away from. Oozing nonchalance, he wheels around the table popping spectacular trick shots while explaining that he wants a good-tasting brew—"even when I'm just showin' off."

Outside the poolroom, appearances aside, Mizerak is a model citizen. Though he has been playing professionally since he was 12, he has never tried to live on his winnings. Instead, he's a teacher of seventh-grade social studies at the William C. McGinnis School in Perth Amboy, N.J. "When I started teaching back in 1968, it was a good job," he explains. "Pool didn't pay a lot and still doesn't."

The beer ad, however, has given Mizerak the kind of exposure that means money in this country. At 35, the four-time U.S. Open pool champ has parlayed his new celebrity into a string of appearances on ABC's Wide World of Sports, a potentially lucrative pool cue endorsement and even a role in the soon-to-be-released movie The Baltimore Bullet with James Coburn and Omar Sharif. "That commercial," says Mizerak, "has changed my life 100 percent."

Well, almost. To the kids in Perth Amboy, he remains Mr. Mizerak, and they needle him sometimes. "It gets to be a bit of a pain," says Mizerak philosophically, "but how can you discipline a kid for that? I like to be the kids' friend, while controlling them. You get more respect from them when you don't bust them for every little thing." He is unperturbed by grumbling from some school officials over his extracurricular activities. "I'm a pretty good teacher, that I know," he counters. "I try to get my work done in school or immediately after so I have nothing over my head pressuring me. I've been teaching long enough to have it down pretty well."

His experience in the classroom pales, of course, beside his lifelong training in the fundamentals of pool. When he was 4, his father, a minor league baseball player and onetime New Jersey state pool champ, bought a Perth Amboy billiard parlor. At first little Steve stood on soda crates to reach his shots. Later his father put in a pool table at home, and built up the floor around it just for his son. By the time he was 12, Steve had become a protégé of world champion Willie Mosconi, a family friend, and was performing in out-of-state exhibitions. The following year he won his hometown championship. In 1962 he captured the state title his father had once held, and in 1970 took the first of his unprecedented four U.S. Opens. In 1976, as a hurricane raged off the New Jersey coast, Mizerak won the World Open at Asbury Park, N.J. with a perfect 150-ball run—a feat his hapless opponent, Rusty Miller, likened to "swimming the English Channel underwater."

Because the purses are modest (usually in four figures), Mizerak takes time away from school to compete in only four or five tournaments a year and rarely practices more than once a week. Divorced a year ago, he lives in a three-bedroom condominium in Fords, N.J. He neither owns a pool table nor encourages his sons Peter, 5, and Stephen, 9, to play. Such an offhand attitude does not mean, however, that Mizerak will be hanging up his customized Balabushka cue—worth $1,200—anytime soon. Last year he won the U.S. Open Nine-Ball Championship in Norfolk, Va., and he is making more commercials for Miller. His heroes, he says, are Mosconi and Ralph Green-leaf, a 1940s champion little known outside the pool halls of America. "When I was growing up, people talked about them everywhere they went," he recalls. "Every poolroom had a picture of them. That's what I wanted to be, and I've got a foothold on that now, I hope."