The shirttail of his Polo shirt hanging loose, Alasdair Gillis, 15-year-old heartthrob of the teen set, gives dear old Dad a hard time. Dad, actor Les Lye, somewhat the worse for wear with his paint-splattered, tattered shirt, two-day growth of beard and hair that looks as if it's been styled by Tina Turner's hairdresser, wants an evening out.

Alasdair sits imperiously in a chair.

"I thought your mother and I would go out," Dad says humbly to the kid with the sprinkle of freckles across his nose.

"I want to know where you're taking her," the youthful interrogator says.

"We thought we'd go to a movie and then to have something to eat," Dad grovels.

"I don't want you back too late," Alasdair warns.

"How about 11 p.m.?" the disheveled parent asks.

It's an "opposite" sketch, a role-reversal bit where kids play the parents and parents suffer the worst kind of overbearing attitudes they sometimes dump on their offspring. The routine is a favorite among the young people who watch " You Can't Do That on Television," a show on the kids' cable network, Nickelodeon. In Houston, the show appears at 6 p.m. daily and at 11 a.m. on Saturdays and Sundays.

Stars of the show, Gillis and Lye, were in town recently for Foley's to promote Green Slime shampoo and soap, products spurred by a popular routine on the show reminiscent of the old sock-it-to-me "Laugh-In" schtick. On "You Can't Do That," kids who say, "I don't know," have green slime, a mixture of flour and green food dye, tossed in their faces.

But the prime targets of the show are adults - not all adults - but pompous, overbearing, stupid, sleazy, irritating adults.

Producer/writer Roger Price had a long string of British hits for children before launching his popular show in Ottawa in 1979. Nickelodeon picked it up in 1982. Price rejected the "Father Knows Best," preachy kind of educational fare in favor of an irreverent slapstick put-down of parents.

And with parents like Dad and dimwitted Val, who always wears rubber gloves (even with formal clothes), childhood anxieties quickly disappear. Who could be afraid of parents who adopt a kid so they'll have someone to take out the garbage? Or worry about sibling rivalry when a mother vacantly says she doesn't much care for any of her kids after her son complains that his brother is her favorite.

"It really is so different from all the other kid shows," Lye said. "He (Price) is doing what the other shows don't do - fun, pure entertainment. The show does have some messages, but that's not the main point."

The main point is to poke fun and give kids a break.

The sketches are fast-moving and set in familiar situations - classrooms, fast-food hangouts, camps. They show youngsters that life at home really isn't so bad if they know the score.

And knowing the score is understanding adults are hiding their faults, but not too well.

Lye's eight to 10 characters give the young set great ammunition to put things into perspective. There's the teacher who has a Hitler moustache and is an idiot. His actions remind children they don't have to suffer fools, no matter how intimidating they seem at first. The tip-off in each sketch is the misspelled word the teacher writes on the blackboard.

Then there's Barth; the kids call him Barf. He's the kind of restaurateur who drives Houston TV consumer advocate Marvin Zindler to sputter and spew. He grinds up cats and other critters for his customers' consumption.

Barf uses one of the catch phrases that send fans into orbit, much like Steve Martin's, "Well, excuse meeeee!" When the kids in a sketch start talking about Barf's maggot-laden food, the character pops up with, "I heard that."

Another pompous adult the kids love to hate is the doctor who cares only for money and golf. His fees are outrageous - $300 after he's given the kid a cure for a headache. And the cure?

"Go stick your head through that window," Lye said, dropping his voice an octave.

Young actors on the show - like Gillis and Christine "Moose" McGlade - are subjected to all means of torture. They're shackled in dungeons, hit with garbage, tied to a stake to be shot by a firing squad. An adult is usually the instrument of the agony.

In the firing squad sketch, for example, a South American general, again played by Lye, shouts, "Fire." Most of the time, the tables are turned by the plucky kids. And the general is the one on the receiving end.

The show aims to make kids the winners.

Price, the producer/writer, thought most educational TV for children ignored the regular kid. It focused on drug abuse, child abuse or family troubles. But the main problems most youths face are in school.

Teachers and other authority figures often seem unfriendly, unfair, always grading and evaluating. Students are watched, pushed, tested and criticized. Pressure that adults would find unnerving goes on unrelentingly. Add to that peer pressure to wear the "right" shoes or clothes, and the kid needs a comic sense simply to survive with his intellect and emotions intact.

"The show is supposed to make kids feel good about themselves, although we don't come out and say that," Alasdair said.

Actors for the show, like the curly-topped Alasdair from Ottawa, are chosen in different ways. Producer Price saw one actor, Kevin Kubacheske, in an airline terminal. The boy was arguing that he should be allowed to fly unescorted. The producer was impressed with his spunk.

Alasdair was part of a drama class and was tapped for a tryout. Now the 8- to 12-year-olds who are the major audience for the show write him 180 letters a week, a sure bet he's someone female viewers would like to green slime. Until his beard sprouts, he'd like to stay with the show, acting as a conduit for sweet revenge against adults who never learned to be kids.

Lye, who has been doing the show since the premiere, is happy with the show's success.

"The kids like it. They see themselves because the kids (on the show) are saying and doing things they either do or would like to do," Lye said. "But they realize it's taking reality one step further."

And that step, humor, makes the unthinkable funny.