While playing the mischievous son, D.J. Conner, on the sitcom Roseanne, Michael Fishman once got himself into a situation that wasn't so comic. On a break from shooting, he hit a baseball that shattered Roseanne's car window. Getting lectured by Roseanne, says the now lanky 19-year-old Fishman, was "just like getting in trouble with my mom."

These days Fishman is learning about parental discipline from the other side. He welcomed son Aaron on Nov. 19,1999, a month after marrying wife Jenny, now 21 and a stay-at-home mom. "People seem to have a hard time dealing with the fact that I am so young and with a family," says Fishman, who proposed to Jenny shortly after they met when he picked up his brother Matthew, now 10, at a daycare center where she worked.

Fishman grew up fast after being selected by Roseanne for the part in 1988. "From the first interview," he says, "I started calling it 'my job.' " Roseanne, too, was sold from the start. "Michael had comedic timing even at 6," she recalls.

After Roseanne went off the air in '97, Fishman continued in 10th grade at a public school where he fell in with a bad crowd, and in an incident that could have been lifted from the show, got suspended briefly for being involved in the theft of a purse. Unhappy at school, he left and earned his diploma through independent study at his parents' Orange County, Calif., home, where he still lives with his wife and baby. (Mom Darlene, 52, teaches nursing, and dad Nelson, 55, runs a cabin-rental business.)

Since Roseanne didn't make him "a ton of money," Fishman says, he welcomes acting gigs (he has a tiny role in A.I.) and hopes one day to buy a house. Meanwhile he has plenty of time to bond with Aaron and coach Little League. "It's very rewarding," says Fishman, "if I make a difference to a kid."